sequence_id stringlengths 7 7 | sequence_name stringlengths 4 573 | sequence listlengths 1 348 | keywords listlengths 1 7 | score int64 1 2.47k | offset_a int64 -14,827 666,262,453B | offset_b int64 0 635M ⌀ | cross_references listlengths 1 128 ⌀ | former_ids listlengths 1 3 ⌀ | author stringlengths 7 231 ⌀ | timestamp timestamp[us]date 1999-12-11 03:00:00 2026-01-19 02:46:49 | filename stringlengths 29 29 | hash stringlengths 32 32 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
A000601 | Expansion of 1/((1-x)^2*(1-x^2)*(1-x^3)). | [
"1",
"2",
"4",
"7",
"11",
"16",
"23",
"31",
"41",
"53",
"67",
"83",
"102",
"123",
"147",
"174",
"204",
"237",
"274",
"314",
"358",
"406",
"458",
"514",
"575",
"640",
"710",
"785",
"865",
"950",
"1041",
"1137",
"1239",
"1347",
"1461",
"1581",
"1... | [
"nonn",
"easy"
] | 135 | 0 | 2 | [
"A000601",
"A002620",
"A006148",
"A006383"
] | [
"M1043",
"N0392"
] | N. J. A. Sloane | 2025-11-05T15:35:22 | oeisdata/seq/A000/A000601.seq | 8dd74d1fa8b7f98d574d9fba5ec67381 |
A000602 | Number of n-node unrooted quartic trees; number of n-carbon alkanes C(n)H(2n+2) ignoring stereoisomers. | [
"1",
"1",
"1",
"1",
"2",
"3",
"5",
"9",
"18",
"35",
"75",
"159",
"355",
"802",
"1858",
"4347",
"10359",
"24894",
"60523",
"148284",
"366319",
"910726",
"2278658",
"5731580",
"14490245",
"36797588",
"93839412",
"240215803",
"617105614",
"1590507121",
"41118... | [
"nonn",
"easy",
"core",
"nice"
] | 232 | 0 | 5 | [
"A000022",
"A000200",
"A000598",
"A000602",
"A000625",
"A000628",
"A067608",
"A067609",
"A067610",
"A144528"
] | [
"M0718",
"N0267"
] | N. J. A. Sloane | 2025-11-05T15:35:22 | oeisdata/seq/A000/A000602.seq | 3f93c38c3252b4773738c3a205d9ab6d |
A000603 | Number of nonnegative solutions to x^2 + y^2 <= n^2. | [
"1",
"3",
"6",
"11",
"17",
"26",
"35",
"45",
"58",
"73",
"90",
"106",
"123",
"146",
"168",
"193",
"216",
"243",
"271",
"302",
"335",
"365",
"402",
"437",
"473",
"516",
"557",
"600",
"642",
"687",
"736",
"782",
"835",
"886",
"941",
"999",
"1050"... | [
"nonn"
] | 52 | 0 | 2 | [
"A000328",
"A000603",
"A036695",
"A036702",
"A255195",
"A255238",
"A302998"
] | [
"M2541",
"N1004"
] | N. J. A. Sloane | 2024-07-18T14:29:28 | oeisdata/seq/A000/A000603.seq | a1d2320f86f7e8ecd34c06a0c21c1797 |
A000604 | Number of nonnegative solutions to x^2 + y^2 + z^2 <= n^2. | [
"1",
"4",
"11",
"29",
"54",
"99",
"163",
"239",
"344",
"486",
"648",
"847",
"1069",
"1355",
"1680",
"2046",
"2446",
"2911",
"3443",
"4022",
"4662",
"5395",
"6145",
"6998",
"7913",
"8913",
"10006",
"11194",
"12437",
"13751",
"15216",
"16710",
"18361",
... | [
"nonn"
] | 28 | 0 | 2 | [
"A000604",
"A000606",
"A302998"
] | [
"M3419",
"N1383"
] | N. J. A. Sloane | 2019-09-29T13:06:18 | oeisdata/seq/A000/A000604.seq | d7de790c1bcbb5410b3a70905e406c5d |
A000605 | Number of points of norm <= n in cubic lattice. | [
"1",
"7",
"33",
"123",
"257",
"515",
"925",
"1419",
"2109",
"3071",
"4169",
"5575",
"7153",
"9171",
"11513",
"14147",
"17077",
"20479",
"24405",
"28671",
"33401",
"38911",
"44473",
"50883",
"57777",
"65267",
"73525",
"82519",
"91965",
"101943",
"113081",
... | [
"nonn"
] | 47 | 0 | 2 | [
"A000605",
"A117609",
"A302997"
] | [
"M4406",
"N1860"
] | N. J. A. Sloane | 2019-09-15T13:48:31 | oeisdata/seq/A000/A000605.seq | 1e9422f42114f839dd1bfb1aee9061e2 |
A000606 | Number of nonnegative solutions to x^2 + y^2 + z^2 <= n. | [
"1",
"4",
"7",
"8",
"11",
"17",
"20",
"20",
"23",
"29",
"35",
"38",
"39",
"45",
"51",
"51",
"54",
"63",
"69",
"72",
"78",
"84",
"87",
"87",
"90",
"99",
"111",
"115",
"115",
"127",
"133",
"133",
"136",
"142",
"151",
"157",
"163",
"169",
"178... | [
"nonn"
] | 38 | 0 | 2 | [
"A000604",
"A000606",
"A002102",
"A117609"
] | [
"M3294",
"N1329"
] | N. J. A. Sloane | 2022-02-01T01:04:15 | oeisdata/seq/A000/A000606.seq | 246d5ea2258a55ec18ac4ac782578bdf |
A000607 | Number of partitions of n into prime parts. | [
"1",
"0",
"1",
"1",
"1",
"2",
"2",
"3",
"3",
"4",
"5",
"6",
"7",
"9",
"10",
"12",
"14",
"17",
"19",
"23",
"26",
"30",
"35",
"40",
"46",
"52",
"60",
"67",
"77",
"87",
"98",
"111",
"124",
"140",
"157",
"175",
"197",
"219",
"244",
"272",
"... | [
"easy",
"nonn",
"nice"
] | 235 | 0 | 6 | [
"A000040",
"A000041",
"A000586",
"A000607",
"A000720",
"A001414",
"A004526",
"A014689",
"A046113",
"A046675",
"A046676",
"A048165",
"A051034",
"A056768",
"A070214",
"A112021",
"A116865",
"A128515",
"A192541",
"A261013",
"A319265",
"A319266",
"A330953",
"A331379",
"A33... | [
"M0265",
"N0093"
] | N. J. A. Sloane | 2025-11-05T15:35:22 | oeisdata/seq/A000/A000607.seq | a69e8d12c4d899068950ef8cb3e49b44 |
A000608 | Number of connected partially ordered sets with n unlabeled elements. | [
"1",
"1",
"1",
"3",
"10",
"44",
"238",
"1650",
"14512",
"163341",
"2360719",
"43944974",
"1055019099",
"32664984238",
"1303143553205",
"66900392672168",
"4413439778321689"
] | [
"hard",
"more",
"nonn",
"nice"
] | 83 | 0 | 4 | [
"A000112",
"A000608",
"A263864",
"A342500"
] | [
"M2864",
"N1152"
] | N. J. A. Sloane, Simon Plouffe, J. A. Wright | 2022-09-04T16:49:31 | oeisdata/seq/A000/A000608.seq | 73406b5988fa1ec7737bc5d423185f57 |
A000609 | Number of threshold functions of n or fewer variables. | [
"2",
"4",
"14",
"104",
"1882",
"94572",
"15028134",
"8378070864",
"17561539552946",
"144130531453121108"
] | [
"nonn",
"hard",
"core",
"nice",
"more"
] | 94 | 0 | 1 | [
"A000609",
"A000615",
"A002077",
"A002080",
"A109456",
"A116986"
] | [
"M1285",
"N0492"
] | N. J. A. Sloane | 2025-06-27T21:47:26 | oeisdata/seq/A000/A000609.seq | 4248e464c2d9bea41dc39836f171f594 |
A000610 | Number of self-complementary Boolean functions of n variables: see Comments for precise definition. | [
"0",
"1",
"2",
"6",
"42",
"4094",
"98210640",
"148947659711650464",
"872404773126414633407736134582136832",
"88627167739308536281147085615274891669779458770791192509009429292662497280"
] | [
"nonn",
"nice",
"easy"
] | 70 | 0 | 3 | [
"A000370",
"A000610",
"A001320",
"A317794"
] | [
"M1714",
"N0678"
] | N. J. A. Sloane | 2025-04-19T18:05:53 | oeisdata/seq/A000/A000610.seq | dbbe37b5fd5d0b5c40c0f12ff13c11a8 |
A000611 | Number of normalized Latin squares of order n containing no 2 X 2 Latin subsquare. | [
"1",
"0",
"1",
"0",
"6",
"40",
"17760",
"2096640",
"29659631400"
] | [
"nonn",
"more"
] | 16 | 1 | 5 | [
"A000611",
"A097548",
"A097549"
] | null | Brendan McKay | 2024-05-19T09:42:14 | oeisdata/seq/A000/A000611.seq | a7fadff5802e01efbb60b21caaf96ed7 |
A000612 | Number of P-equivalence classes of switching functions of n or fewer variables, divided by 2. | [
"1",
"2",
"6",
"40",
"1992",
"18666624",
"12813206169137152",
"33758171486592987164087845043830784",
"1435913805026242504952006868879460423834904914948818373264705576411070464"
] | [
"nonn",
"easy",
"nice",
"core"
] | 72 | 0 | 2 | [
"A000612",
"A003180",
"A007716",
"A055621",
"A058891",
"A283877",
"A300913",
"A306005",
"A317533",
"A317757"
] | [
"M1712",
"N0677"
] | N. J. A. Sloane | 2024-12-23T11:38:10 | oeisdata/seq/A000/A000612.seq | fc9df6d543a960dbd4a4e6550a8827d2 |
A000613 | Number of Boolean functions of n variables. | [
"2",
"4",
"10",
"46",
"1372",
"475499108",
"1038397981840994509577948",
"10825608503765473087803384381127710579846422820261084889808"
] | [
"nonn",
"easy",
"nice"
] | 27 | 1 | 1 | [
"A000585",
"A000613"
] | [
"M1241",
"N0475"
] | N. J. A. Sloane | 2022-10-30T15:43:13 | oeisdata/seq/A000/A000613.seq | 926824235d6ae16e823c875c9c015e77 |
A000614 | Number of complemented types of Boolean functions of n variables under action of AG(n,2). | [
"2",
"3",
"6",
"18",
"206",
"7888299",
"8112499583888855378066",
"42287533217833953489054778023401252726576585396037133766"
] | [
"nonn",
"easy",
"nice"
] | 36 | 1 | 1 | [
"A000214",
"A000614"
] | [
"M0815",
"N0307"
] | N. J. A. Sloane | 2022-06-17T16:14:39 | oeisdata/seq/A000/A000614.seq | 8ff1f07cfb976640d7b6de9f44986001 |
A000615 | Threshold functions of exactly n variables. | [
"2",
"2",
"8",
"72",
"1536",
"86080",
"14487040",
"8274797440",
"17494930604032"
] | [
"nonn",
"more"
] | 33 | 0 | 1 | [
"A000609",
"A000615"
] | [
"M0379",
"N0142",
"N0747"
] | N. J. A. Sloane | 2025-06-27T21:46:34 | oeisdata/seq/A000/A000615.seq | 187d53711a5a03f06c502aebc8b26d6a |
A000616 | a(-1)=1 by convention; for n >= 0, a(n) = number of irreducible Boolean functions of n variables. | [
"1",
"2",
"3",
"6",
"22",
"402",
"1228158",
"400507806843728",
"527471432057653004017274030725792",
"11218076601767519586965281984173341005925142853855481024470471657123840"
] | [
"nonn",
"easy",
"nice"
] | 111 | -1 | 2 | [
"A000231",
"A000616",
"A000618",
"A003180",
"A039754",
"A102449",
"A109460",
"A109462",
"A361870"
] | [
"M0819",
"N0310",
"N1026"
] | N. J. A. Sloane | 2025-11-06T03:33:47 | oeisdata/seq/A000/A000616.seq | 0f943ff000cc440bfdf287794ea131aa |
A000617 | Number of NP-equivalence classes of threshold functions of n or fewer variables. | [
"2",
"3",
"5",
"10",
"27",
"119",
"1113",
"29375",
"2730166",
"989913346"
] | [
"nonn",
"hard",
"more",
"nice"
] | 55 | 0 | 1 | [
"A000617",
"A000619"
] | [
"M0727",
"N0272"
] | N. J. A. Sloane | 2025-11-05T15:21:39 | oeisdata/seq/A000/A000617.seq | c4e6a2770fed3d61e5729423f86f03f3 |
A000618 | Number of nondegenerate Boolean functions of n variables: For n > 0, a(n) = A000616(n) - A000616(n-1). | [
"2",
"1",
"3",
"16",
"380",
"1227756",
"400507805615570",
"527471432057653003616766223882064",
"11218076601767519586965281984173341005397671421797828020453197626398048"
] | [
"nonn",
"nice"
] | 51 | 0 | 1 | [
"A000371",
"A000616",
"A000618",
"A211705",
"A211706"
] | [
"M0160",
"N0063"
] | N. J. A. Sloane | 2025-11-06T03:33:30 | oeisdata/seq/A000/A000618.seq | 2846d93f48835bf6e2242b4c19ce6d2b |
A000619 | NP-equivalence classes of threshold functions of exactly n variables. | [
"2",
"1",
"2",
"5",
"17",
"92",
"994",
"28262",
"2700791",
"990331318"
] | [
"nonn",
"more"
] | 49 | 0 | 1 | [
"A000617",
"A000619"
] | [
"M0121",
"N0048"
] | N. J. A. Sloane | 2025-06-27T21:47:06 | oeisdata/seq/A000/A000619.seq | da39954ccf65f78cb5a70bb35b241d55 |
A000620 | Number of monosubstituted alkanes C(n-1)H(2n-1)-X with n-1 carbon atoms that are stereoisomers. | [
"0",
"0",
"0",
"0",
"2",
"6",
"20",
"60",
"176",
"512",
"1488",
"4326",
"12648",
"37186",
"109980",
"327216",
"979020",
"2944414",
"8897732",
"27005290",
"82288516",
"251650788",
"772127678",
"2376238138",
"7333188770",
"22688297950",
"70360977228",
"21867881802... | [
"nonn"
] | 29 | 1 | 5 | [
"A000620",
"A000621",
"A000622",
"A000623",
"A000624",
"A000625",
"A239803",
"A239805"
] | [
"M1642",
"N0642"
] | N. J. A. Sloane | 2022-07-18T11:24:24 | oeisdata/seq/A000/A000620.seq | 052c75641f81d375c80e4522daed1365 |
A000621 | Number of monosubstituted alkanes C(n-1)H(2n-1)-X with n-1 carbon atoms that are not stereoisomers. | [
"1",
"1",
"1",
"2",
"3",
"5",
"8",
"14",
"23",
"39",
"65",
"110",
"184",
"310",
"520",
"876",
"1471",
"2475",
"4159",
"6996",
"11759",
"19775",
"33244",
"55902",
"93984",
"158030",
"265696",
"446746",
"751128",
"1262940",
"2123444",
"3570318",
"6002983... | [
"nonn",
"nice",
"easy"
] | 90 | 1 | 4 | [
"A000620",
"A000621",
"A000625",
"A239804",
"A239806"
] | [
"M0697",
"N0258"
] | N. J. A. Sloane | 2022-06-02T03:29:07 | oeisdata/seq/A000/A000621.seq | 3c551ea9d527c5fb6a9289d956b614ac |
A000622 | Number of monosubstituted alkanes C(n)H(2n+1)-X of the form shown in the Comments lines that are stereoisomers. | [
"0",
"0",
"0",
"2",
"4",
"14",
"34",
"98",
"270",
"768",
"2192",
"6360",
"18576",
"54780",
"162658",
"486154",
"1461174",
"4413988",
"13393816",
"40807290",
"124783604",
"382842018",
"1178140170",
"3635626680",
"11247841040",
"34880346840",
"108402132234",
"3375... | [
"nonn"
] | 20 | 1 | 4 | [
"A000620",
"A000622",
"A000625",
"A239803",
"A239807"
] | [
"M1272",
"N0490"
] | N. J. A. Sloane | 2022-02-01T01:05:20 | oeisdata/seq/A000/A000622.seq | b75ce7c276bd1cb3b41304549ace3f00 |
A000623 | Number of monosubstituted alkanes C(n)H(2n+1)-X of the form shown in the Comments lines that are stereoisomers. | [
"0",
"0",
"0",
"0",
"0",
"0",
"6",
"18",
"66",
"208",
"646",
"1962",
"5962",
"18014",
"54578",
"165650",
"504220",
"1539330",
"4713742",
"14475936",
"44578668",
"137634872",
"425970290",
"1321323952",
"4107268140",
"12792332438",
"39915708564",
"124762612530",
... | [
"nonn"
] | 21 | 1 | 7 | [
"A000620",
"A000623",
"A000625",
"A239803",
"A239808"
] | [
"M4125",
"N1712"
] | N. J. A. Sloane | 2022-02-01T01:05:40 | oeisdata/seq/A000/A000623.seq | 1a26c5295ff5468dac4f29fdf4a7b506 |
A000624 | Number of monosubstituted alkanes C(n)H(2n+1)-X of the form shown in the Comments lines that are not stereoisomers. | [
"0",
"0",
"0",
"1",
"1",
"3",
"4",
"9",
"13",
"26",
"40",
"74",
"118",
"210",
"342",
"595",
"981",
"1684",
"2798",
"4763",
"7951",
"13469",
"22548",
"38082",
"63862",
"107666",
"180740",
"304382",
"511292",
"860504",
"1445998",
"2432665",
"4088805",
... | [
"nonn"
] | 23 | 1 | 6 | [
"A000620",
"A000624",
"A000625",
"A239804",
"A239809"
] | [
"M2355",
"N0932"
] | N. J. A. Sloane | 2022-02-01T01:06:00 | oeisdata/seq/A000/A000624.seq | 4f6979acfed95610bdd0593a045a9326 |
A000625 | Number of n-node steric rooted ternary trees; number of n carbon alkyl radicals C(n)H(2n+1) taking stereoisomers into account. | [
"1",
"1",
"1",
"2",
"5",
"11",
"28",
"74",
"199",
"551",
"1553",
"4436",
"12832",
"37496",
"110500",
"328092",
"980491",
"2946889",
"8901891",
"27012286",
"82300275",
"251670563",
"772160922",
"2376294040",
"7333282754",
"22688455980",
"70361242924",
"2186792647... | [
"nonn",
"easy",
"nice"
] | 73 | 0 | 4 | [
"A000598",
"A000602",
"A000620",
"A000624",
"A000625",
"A000628",
"A010732",
"A010733",
"A086194",
"A086200",
"A239803",
"A239810"
] | [
"M1402",
"N0546"
] | N. J. A. Sloane | 2019-02-17T20:45:45 | oeisdata/seq/A000/A000625.seq | 32d36600f1884d04325eee14c438628b |
A000626 | Number of stereoisomeric paraffins with n carbon atoms. | [
"0",
"0",
"0",
"0",
"0",
"0",
"4",
"11",
"35",
"101",
"290",
"804",
"2256",
"6296",
"17689",
"49952",
"142016",
"406330",
"1170272",
"3390932",
"9882412",
"28955403",
"85261439",
"252213192",
"749250700",
"2234562027",
"6688670232",
"20088920730",
"60525912003... | [
"nonn"
] | 19 | 1 | 7 | [
"A000626",
"A000627",
"A000628"
] | [
"M3422",
"N1386"
] | N. J. A. Sloane | 2022-02-01T01:06:20 | oeisdata/seq/A000/A000626.seq | 8f659bd224bd5d50216bdb8776f0f75f |
A000627 | Number of non-stereoisomeric paraffins with n carbon atoms. | [
"1",
"1",
"1",
"2",
"3",
"5",
"7",
"13",
"20",
"35",
"55",
"96",
"156",
"267",
"438",
"747",
"1239",
"2099",
"3498",
"5912",
"9890",
"16677",
"27951",
"47084",
"79019",
"133003",
"223373",
"375824",
"631477",
"1062160",
"1785159",
"3002227",
"5046641",... | [
"nonn"
] | 20 | 1 | 4 | [
"A000626",
"A000627",
"A000628"
] | [
"M0674",
"N0249"
] | N. J. A. Sloane | 2022-02-01T01:06:37 | oeisdata/seq/A000/A000627.seq | 5df73e81bdf9bf1d2166be8cd90650a7 |
A000628 | Number of n-node unrooted steric quartic trees; number of n-carbon alkanes C(n)H(2n+2) taking stereoisomers into account. | [
"1",
"1",
"1",
"1",
"2",
"3",
"5",
"11",
"24",
"55",
"136",
"345",
"900",
"2412",
"6563",
"18127",
"50699",
"143255",
"408429",
"1173770",
"3396844",
"9892302",
"28972080",
"85289390",
"252260276",
"749329719",
"2234695030",
"6688893605",
"20089296554",
"605... | [
"nonn",
"easy",
"nice"
] | 71 | 0 | 5 | [
"A000598",
"A000602",
"A000625",
"A000626",
"A000627",
"A000628",
"A010372",
"A010373",
"A086194",
"A086200"
] | [
"M0732",
"N0274"
] | N. J. A. Sloane | 2025-04-07T11:59:59 | oeisdata/seq/A000/A000628.seq | cd7de270fb62934b0c88656e550724b6 |
A000629 | Number of necklaces of partitions of n+1 labeled beads. | [
"1",
"2",
"6",
"26",
"150",
"1082",
"9366",
"94586",
"1091670",
"14174522",
"204495126",
"3245265146",
"56183135190",
"1053716696762",
"21282685940886",
"460566381955706",
"10631309363962710",
"260741534058271802",
"6771069326513690646",
"185603174638656822266",
"535537559248... | [
"nonn",
"easy",
"eigen",
"nice"
] | 319 | 0 | 2 | [
"A000629",
"A000670",
"A002050",
"A008277",
"A008965",
"A028246",
"A052856",
"A052861",
"A076726",
"A127671",
"A241168",
"A263634"
] | null | N. J. A. Sloane, Don Knuth, Nick Singer (nsinger(AT)eos.hitc.com) | 2025-12-12T09:49:44 | oeisdata/seq/A000/A000629.seq | 229414fd5359273eef8eaea41c61b6b9 |
A000630 | Number of ways to represent n using the binary operator a * b = 2^a + b. | [
"1",
"1",
"2",
"3",
"7",
"12",
"23",
"41",
"81",
"149",
"282",
"522",
"987",
"1843",
"3463",
"6473",
"12160",
"22773",
"42719",
"80025",
"150074",
"281258",
"527320",
"988334",
"1852849",
"3473061",
"6510681",
"12204139",
"22877649",
"42884585",
"80389797"... | [
"nonn",
"easy",
"nice"
] | 38 | 0 | 3 | null | null | N. J. A. Sloane | 2021-12-19T09:39:34 | oeisdata/seq/A000/A000630.seq | fffa2fcfc7ac7811c4c7090303419c1d |
A000631 | Number of ethylene derivatives with n carbon atoms. | [
"1",
"1",
"3",
"5",
"13",
"27",
"66",
"153",
"377",
"914",
"2281",
"5690",
"14397",
"36564",
"93650",
"240916",
"623338",
"1619346",
"4224993",
"11062046",
"29062341",
"76581151",
"202365823",
"536113477",
"1423665699",
"3788843391",
"10103901486",
"26995498151"... | [
"nonn"
] | 78 | 2 | 3 | [
"A000598",
"A000631",
"A000642",
"A027852"
] | [
"M2490",
"N0987"
] | N. J. A. Sloane | 2020-12-06T14:02:13 | oeisdata/seq/A000/A000631.seq | 11d4f98c6f740b48721de91ac6953714 |
A000632 | Number of esters with n carbon atoms up to structural isomerism. | [
"1",
"2",
"4",
"9",
"20",
"45",
"105",
"249",
"599",
"1463",
"3614",
"9016",
"22695",
"57564",
"146985",
"377555",
"974924",
"2529308",
"6589734",
"17234114",
"45228343",
"119069228",
"314368027",
"832193902",
"2208347917",
"5873364623",
"15653499416",
"41800070... | [
"nonn"
] | 40 | 2 | 2 | null | [
"M1174",
"N0451"
] | N. J. A. Sloane | 2025-02-05T10:12:54 | oeisdata/seq/A000/A000632.seq | 8f0aab67f5b83e70fcc17e16b267bef0 |
A000633 | Number of acyclic quaternary ammonium ions with n carbon atoms. | [
"1",
"1",
"3",
"7",
"18",
"42",
"109",
"269",
"691",
"1759",
"4542",
"11733",
"30559",
"79743",
"209136",
"549959",
"1451178",
"3838925",
"10182703",
"27069940",
"72121696",
"192527888",
"514908269",
"1379454526",
"3701556642",
"9947456861",
"26770280299",
"7213... | [
"nonn"
] | 27 | 4 | 3 | [
"A000598",
"A000633"
] | [
"M2667",
"N1065"
] | N. J. A. Sloane | 2023-05-21T22:22:42 | oeisdata/seq/A000/A000633.seq | ef08d0a3fe7fcf87945e241c53a7465f |
A000634 | Number of glycols with n carbon atoms. | [
"1",
"2",
"6",
"14",
"38",
"97",
"260",
"688",
"1856",
"4994",
"13550",
"36791",
"100302",
"273824",
"749316",
"2053247",
"5635266",
"15484532",
"42599485",
"117312742",
"323373356",
"892139389",
"2463252315",
"6806148956",
"18818714543",
"52065725034",
"144135111... | [
"nonn"
] | 26 | 2 | 2 | [
"A000634",
"A000636",
"A000642"
] | [
"M1604",
"N0627"
] | N. J. A. Sloane | 2018-01-22T19:26:12 | oeisdata/seq/A000/A000634.seq | b4009c0e2a8f817bb7cd3c6e921e904a |
A000635 | Number of paraffins C_n H_{2n} X Y with n carbon atoms. | [
"0",
"1",
"2",
"5",
"12",
"31",
"80",
"210",
"555",
"1479",
"3959",
"10652",
"28760",
"77910",
"211624",
"576221",
"1572210",
"4297733",
"11767328",
"32266801",
"88594626",
"243544919",
"670228623",
"1846283937",
"5090605118",
"14047668068",
"38794922293",
"1072... | [
"nonn",
"easy",
"nice"
] | 39 | 0 | 3 | null | [
"M1418",
"N0555"
] | N. J. A. Sloane | 2021-12-19T09:40:21 | oeisdata/seq/A000/A000635.seq | f8c8d4526821228ae2dbc3b61244e7d5 |
A000636 | Number of paraffins C_n H_{2n} X_2 with n carbon atoms. | [
"1",
"2",
"4",
"9",
"21",
"52",
"129",
"332",
"859",
"2261",
"5983",
"15976",
"42836",
"115469",
"312246",
"847241",
"2304522",
"6283327",
"17164401",
"46972357",
"128741107",
"353345434",
"970999198",
"2671347292",
"7356752678",
"20279171785",
"55948407837",
"1... | [
"nonn",
"easy",
"nice"
] | 28 | 1 | 2 | null | [
"M1185",
"N0457"
] | N. J. A. Sloane | 2022-01-29T00:59:56 | oeisdata/seq/A000/A000636.seq | 9740f1aa7e25c3c95f99e203beab2e50 |
A000637 | Number of fixed-point-free permutation groups of degree n. | [
"1",
"0",
"1",
"2",
"7",
"8",
"37",
"40",
"200",
"258",
"1039",
"1501",
"7629",
"10109",
"54322",
"83975",
"527036",
"780193",
"5808293"
] | [
"nonn",
"hard",
"more",
"nice"
] | 57 | 0 | 4 | [
"A000001",
"A000019",
"A000637",
"A000638",
"A002106",
"A005226",
"A005432",
"A116693"
] | [
"M1730",
"N0685"
] | N. J. A. Sloane | 2025-08-17T21:11:10 | oeisdata/seq/A000/A000637.seq | 28cfb8f5bf3cb272582919e26893c033 |
A000638 | Number of permutation groups of degree n; also number of conjugacy classes of subgroups of symmetric group S_n; also number of molecular species of degree n. | [
"1",
"1",
"2",
"4",
"11",
"19",
"56",
"96",
"296",
"554",
"1593",
"3094",
"10723",
"20832",
"75154",
"159129",
"686165",
"1466358",
"7274651"
] | [
"nonn",
"hard",
"more",
"nice"
] | 86 | 0 | 3 | [
"A000001",
"A000019",
"A000637",
"A000638",
"A005432"
] | [
"M1244",
"N0477"
] | N. J. A. Sloane | 2025-11-05T15:21:39 | oeisdata/seq/A000/A000638.seq | 54226244c92445a02d239982c663c50f |
A000639 | Number of alkyl benzenes with n carbon atoms: C(n)H(2n-6). | [
"0",
"0",
"0",
"0",
"0",
"1",
"1",
"4",
"8",
"22",
"51",
"136",
"335",
"871",
"2217",
"5749",
"14837",
"38636",
"100622",
"263381",
"690709",
"1817544",
"4793449",
"12675741",
"33592349",
"89223734",
"237455566",
"633176939",
"1691377956",
"4525792533",
"1... | [
"nonn",
"easy",
"nice"
] | 43 | 1 | 8 | [
"A000598",
"A000639"
] | [
"M3341",
"N1344"
] | N. J. A. Sloane | 2025-11-05T15:21:39 | oeisdata/seq/A000/A000639.seq | 8a5260f8db065b70fe5d5258e2fc4c04 |
A000640 | Number of paraffins C_n H_{2n-1} XYZ with n carbon atoms. | [
"0",
"1",
"4",
"13",
"42",
"131",
"402",
"1218",
"3657",
"10899",
"32298",
"95257",
"279844",
"819390",
"2392392",
"6967956",
"20250974",
"58744089",
"170118980",
"491913999",
"1420493862",
"4096940530",
"11803172152",
"33970257473",
"97678027311",
"280624328431",
... | [
"nonn",
"easy"
] | 27 | 0 | 3 | [
"A000598",
"A000640",
"A000642"
] | [
"M3466",
"N1410"
] | N. J. A. Sloane | 2021-12-19T09:41:06 | oeisdata/seq/A000/A000640.seq | 946efda426290bea1a80adbbe532d374 |
A000641 | Number of paraffins C_n H_{2n-1} X_3 with n carbon atoms. | [
"0",
"1",
"2",
"5",
"14",
"39",
"109",
"312",
"890",
"2552",
"7325",
"21047",
"60465",
"173750",
"499068",
"1433071",
"4113105",
"11799780",
"33834367",
"96968462",
"277771344",
"795310628",
"2276055442",
"6510786627",
"18616389094",
"53207964655",
"152014267327",... | [
"nonn",
"easy"
] | 19 | 0 | 3 | null | [
"M1456",
"N0575"
] | N. J. A. Sloane | 2022-02-01T01:06:53 | oeisdata/seq/A000/A000641.seq | 56df966cdc2c8e6ac134570c54546c1a |
A000642 | a(1)=0; for n>1, a(n) = number of isomeric hydrocarbons of the acetylene series with carbon content n. | [
"0",
"1",
"1",
"2",
"3",
"7",
"14",
"32",
"72",
"171",
"405",
"989",
"2426",
"6045",
"15167",
"38422",
"97925",
"251275",
"648061",
"1679869",
"4372872",
"11428365",
"29972078",
"78859809",
"208094977",
"550603722",
"1460457242",
"3882682803",
"10344102122",
... | [
"nonn",
"easy",
"nice"
] | 73 | 1 | 4 | [
"A000598",
"A000642",
"A002094"
] | [
"M0839",
"N0318"
] | N. J. A. Sloane | 2020-11-29T08:18:48 | oeisdata/seq/A000/A000642.seq | ef104169d81ed8affc44d636a8989a72 |
A000643 | a(n) = a(n-1) + 2^a(n-2). | [
"0",
"0",
"1",
"2",
"4",
"8",
"24",
"280",
"16777496",
"1942668892225729070919461906823518906642406839052139521251812409738904285205225275672"
] | [
"nonn"
] | 21 | 0 | 4 | [
"A000643",
"A000659"
] | null | N. J. A. Sloane | 2024-01-05T19:14:02 | oeisdata/seq/A000/A000643.seq | 677efa586bb4eeaf41d69961dd60281b |
A000644 | Number of loops of length 4n on square grid that turn at each step and return to start in original direction. | [
"1",
"1",
"3",
"7",
"31",
"138",
"808",
"4956",
"33047",
"227328",
"1614793",
"11710299",
"86495618",
"648399937",
"4923728056"
] | [
"nonn",
"more",
"nice",
"walk"
] | 26 | 1 | 3 | null | null | N. J. A. Sloane | 2022-06-17T03:18:37 | oeisdata/seq/A000/A000644.seq | 3bf8a57f78e88a7737210284fd73a4db |
A000645 | Number of alkyls X^{II} C_n H_{2n+1} Y with n carbon atoms. | [
"1",
"2",
"4",
"10",
"25",
"64",
"166",
"437",
"1157",
"3087",
"8276",
"22287",
"60230",
"163284",
"443820",
"1209155",
"3300890",
"9027337",
"24727437",
"67829684",
"186302693",
"512301120",
"1410237805",
"3885803531",
"10716571591",
"29579231200",
"81704634803",... | [
"nonn",
"easy"
] | 19 | 0 | 2 | null | [
"M1209",
"N0467"
] | N. J. A. Sloane | 2022-02-01T01:07:09 | oeisdata/seq/A000/A000645.seq | 3c2829b084c4b6d655dee14468cdf055 |
A000646 | Number of alkyls Y^{II} C_n H_{2n+2} with n carbon atoms. | [
"1",
"2",
"3",
"6",
"13",
"28",
"62",
"144",
"338",
"810",
"1970",
"4852",
"12073",
"30334",
"76805",
"195850",
"502461",
"1296122",
"3359527",
"8745744",
"22856223",
"59944156",
"157718380",
"416189954",
"1101204387",
"2920914484",
"7765357967",
"20688204244",
... | [
"nonn",
"easy"
] | 18 | 0 | 2 | null | [
"M0800",
"N0303"
] | N. J. A. Sloane | 2022-02-01T01:07:23 | oeisdata/seq/A000/A000646.seq | 750e0581fa9b70041f754294f4eaff30 |
A000647 | Alkyl naphthalenes C_{n+10} H_{2n+8} with n+10 carbon atoms. | [
"1",
"2",
"12",
"32",
"110",
"310",
"920",
"2558",
"7177",
"19660",
"53864",
"146180",
"396296",
"1070296",
"2888662",
"7785856",
"20982905",
"56536762",
"152378548",
"410825678",
"1108224556",
"2991244712",
"8079252116",
"21837144430",
"59066580606",
"159886668880"... | [
"nonn",
"easy"
] | 17 | 0 | 2 | null | [
"M2018",
"N0798"
] | N. J. A. Sloane | 2022-02-01T01:07:41 | oeisdata/seq/A000/A000647.seq | 8dd5ef85e8bf06c68b5e1718d620dad6 |
A000648 | Number of alkyls C_{n+15} H_{2n+10} (Anthr.) with n carbon atoms. | [
"1",
"3",
"18",
"61",
"225",
"716",
"2272",
"6826",
"20238",
"58552",
"167625",
"473929",
"1330490",
"3709591",
"10296336",
"28466065",
"78481065",
"215878221",
"592832960",
"1625887129",
"4454936029",
"12198071235",
"33383810793",
"91336813784",
"249851178964",
"68... | [
"nonn",
"easy"
] | 21 | 0 | 2 | [
"A000648",
"A000649"
] | [
"M3045",
"N1235"
] | N. J. A. Sloane | 2021-12-19T09:41:37 | oeisdata/seq/A000/A000648.seq | 34488697e9d82f1f08bea3fd1c2f1fe4 |
A000649 | Number of alkyls C_{n+15} H_{2n+10} (Phenan) with n carbon atoms. | [
"1",
"5",
"30",
"115",
"425",
"1396",
"4440",
"13470",
"40000",
"116140",
"332827",
"942435",
"2647450",
"7386925",
"20511620",
"56731383",
"156451985",
"430462915",
"1182341890",
"3243215495",
"8887664047",
"24338341165",
"66616422775",
"182276901760",
"498657609720"... | [
"nonn",
"easy"
] | 20 | 0 | 2 | [
"A000648",
"A000649"
] | [
"M3958",
"N1633"
] | N. J. A. Sloane | 2022-02-01T01:07:58 | oeisdata/seq/A000/A000649.seq | c482b6f63d4f11721fc0bac28d66354f |
A000650 | Number of alkyls S C_{n+4} H_{2n+4} with n carbon atoms. | [
"1",
"2",
"6",
"12",
"31",
"72",
"178",
"430",
"1071",
"2654",
"6680",
"16858",
"42926",
"109778",
"282490",
"730028",
"1895456",
"4940094",
"12923600",
"33919416",
"89301052",
"235762572",
"624057892",
"1655817422",
"4403189781",
"11733247076",
"31326037116",
"... | [
"nonn",
"easy",
"nice"
] | 27 | 0 | 2 | null | [
"M1588",
"N0618"
] | N. J. A. Sloane | 2021-12-19T09:41:49 | oeisdata/seq/A000/A000650.seq | 931bbf5655f097b5ffeb83ee8ce9b1c1 |
A000651 | Running time of Takeuchi function. | [
"0",
"1",
"4",
"14",
"53",
"223",
"1034",
"5221",
"28437",
"165859",
"1029803",
"6772850",
"46983238",
"342509396",
"2615606677",
"20865444825",
"173446634597",
"1499111445237",
"13445550920288",
"124919896067530",
"1200320663197275",
"11910845573790488"
] | [
"nonn"
] | 42 | 0 | 3 | [
"A000651",
"A143307"
] | null | N. J. A. Sloane | 2025-11-05T15:21:39 | oeisdata/seq/A000/A000651.seq | 7d04495479d02d518977cbd627f970b1 |
A000652 | Invertible Boolean functions of n variables. | [
"1",
"1",
"6",
"924",
"81738720000",
"256963707943061374889193111552000",
"30978254928194376001814792318154658399138184007229852126545533479881553257431040000000"
] | [
"nonn",
"easy"
] | 21 | 0 | 3 | [
"A000652",
"A000653",
"A000654",
"A000722",
"A001038",
"A001537",
"A046856",
"A046857"
] | [
"M4315",
"N1807"
] | N. J. A. Sloane | 2022-02-01T01:08:43 | oeisdata/seq/A000/A000652.seq | 85294131ccce19bb43ab4b0825d345b3 |
A000653 | Invertible Boolean functions of n variables. | [
"2",
"7",
"1172",
"36325278240",
"18272974787063551687986348306336",
"244766458691906180755079840538506099505695351680436638205950721844523539763881615360"
] | [
"nonn"
] | 56 | 1 | 1 | null | [
"M1821",
"N0723"
] | N. J. A. Sloane | 2025-11-05T15:21:39 | oeisdata/seq/A000/A000653.seq | f361b40580594fdd7101ee16d855efc4 |
A000654 | Invertible Boolean functions of n variables. | [
"1",
"2",
"52",
"142090700",
"17844701940501123640681816160",
"59757436204078657410908164193971330396709572693816353610758085074676243846093824"
] | [
"nonn"
] | 45 | 1 | 2 | null | [
"M2173",
"N0868"
] | N. J. A. Sloane | 2025-06-11T17:51:46 | oeisdata/seq/A000/A000654.seq | e78f26c9879abff3610d063a37073229 |
A000655 | a(n) = number of letters in a(n-1), a(1) = 1 (in English). | [
"1",
"3",
"5",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"4",
"... | [
"nonn",
"word",
"easy"
] | 33 | 1 | 2 | [
"A000655",
"A005589",
"A061504",
"A101432",
"A328263"
] | null | N. J. A. Sloane | 2024-06-26T09:33:32 | oeisdata/seq/A000/A000655.seq | 7a9f1b9d8bd9fa77bbd09c9922b727e1 |
A000656 | Invertible Boolean functions of n variables with S(n) acting on the domain and GL(n,2) acting on the range. | [
"2",
"3",
"56",
"43265712",
"219289731988435167257927904",
"8742218740996073061357349746759733054713953086811227917496519524423937904640"
] | [
"nonn"
] | 23 | 1 | 1 | null | [
"M0924",
"N0348"
] | N. J. A. Sloane | 2022-02-01T01:09:03 | oeisdata/seq/A000/A000656.seq | 519c7b0422774cfa4426b469227bc54d |
A000657 | Median Euler numbers (the middle numbers of Arnold's shuttle triangle). | [
"1",
"1",
"4",
"46",
"1024",
"36976",
"1965664",
"144361456",
"13997185024",
"1731678144256",
"266182076161024",
"49763143319190016",
"11118629668610842624",
"2925890822304510631936",
"895658946905031792553984",
"315558279782214450517374976",
"126780706777739389745128013824"
] | [
"nonn",
"nice",
"easy"
] | 101 | 0 | 3 | [
"A000657",
"A002832",
"A005799",
"A084938",
"A098277",
"A099023",
"A323834"
] | null | N. J. A. Sloane and Don Knuth | 2025-09-24T06:13:44 | oeisdata/seq/A000/A000657.seq | 7b69553ea1ba5f8e6d6964f1dc982499 |
A000658 | Strehl's sequence "C_n^(3)". | [
"1",
"4",
"68",
"1732",
"51076",
"1657904",
"57793316",
"2117525792",
"80483121028",
"3147565679824",
"125937573689968",
"5133632426499152",
"212530848994367524",
"8914634034287235856",
"378138515326996979168",
"16196097181014298854032"
] | [
"nonn",
"easy",
"nice"
] | 27 | 0 | 2 | [
"A000658",
"A007318",
"A094424"
] | null | Don Knuth | 2015-09-09T23:51:09 | oeisdata/seq/A000/A000658.seq | 850fac7ca5cbbe26da31172af951b7bc |
A000659 | a(n) = 2^a(n-1) + a(n-2). | [
"0",
"0",
"1",
"2",
"5",
"34",
"17179869189"
] | [
"nonn"
] | 16 | 0 | 4 | [
"A000643",
"A000659"
] | null | N. J. A. Sloane | 2022-04-09T11:36:51 | oeisdata/seq/A000/A000659.seq | 64c19e5487369877ec3e03519533fe13 |
A000660 | Boustrophedon transform of 1,1,2,3,4,5,... | [
"1",
"2",
"5",
"14",
"41",
"136",
"523",
"2330",
"11857",
"67912",
"432291",
"3027166",
"23125673",
"191389108",
"1705788659",
"16289080922",
"165919213089",
"1795666675824",
"20576824369027",
"248892651678198",
"3168999664907705",
"42366404751871660",
"593368400878431795... | [
"nonn"
] | 55 | 0 | 2 | [
"A000111",
"A000660",
"A028310",
"A109449",
"A231179"
] | null | N. J. A. Sloane, Simon Plouffe | 2025-11-10T21:50:37 | oeisdata/seq/A000/A000660.seq | 38d6c9c1f20212b8fdeb348b3a7ed510 |
A000661 | Shifts 2 places left under boustrophedon transform. | [
"1",
"0",
"1",
"1",
"2",
"6",
"17",
"62",
"259",
"1230",
"6592",
"39313",
"258575",
"1860318",
"14538245",
"122670593",
"1111715644",
"10771412394",
"111125142979",
"1216309735378",
"14078811306851",
"171837279141312",
"2205768169095338",
"29707098687614285"
] | [
"nonn",
"eigen"
] | 24 | 0 | 5 | null | null | N. J. A. Sloane | 2022-02-01T01:09:28 | oeisdata/seq/A000/A000661.seq | 247e0765a1bf66d16d4d4f5f37c39e1e |
A000662 | Number of relations with 3 arguments on n nodes. | [
"2",
"136",
"22377984",
"768614354122719232",
"354460798875983863749270670915141632",
"146267071761884981524915186989628577728537526896649216991428608"
] | [
"nonn",
"nice"
] | 42 | 1 | 1 | [
"A000595",
"A000662",
"A001377",
"A051241"
] | [
"M2180",
"N0872"
] | N. J. A. Sloane | 2024-07-02T15:02:08 | oeisdata/seq/A000/A000662.seq | cc88163ed41c3521277d478debf1face |
A000663 | Number of relations on an infinite set. | [
"1",
"2",
"9",
"37",
"183",
"933",
"5314",
"32043",
"207212",
"1415934",
"10200289",
"77018442",
"607474564",
"4987909231",
"42519634303",
"375395726926"
] | [
"nonn",
"nice",
"more"
] | 29 | 0 | 2 | null | [
"M1932",
"N0763"
] | N. J. A. Sloane | 2025-12-15T12:17:47 | oeisdata/seq/A000/A000663.seq | 3874fc0fba4665c82ae7752a45ee866f |
A000664 | Number of graphs with n edges. | [
"1",
"1",
"2",
"5",
"11",
"26",
"68",
"177",
"497",
"1476",
"4613",
"15216",
"52944",
"193367",
"740226",
"2960520",
"12334829",
"53394755",
"239544624",
"1111261697",
"5320103252",
"26237509076",
"133087001869",
"693339241737",
"3705135967663",
"20286965943329",
... | [
"nonn",
"nice"
] | 69 | 0 | 3 | [
"A000055",
"A000088",
"A000664",
"A002905",
"A008406",
"A053418",
"A275421"
] | [
"M1400",
"N0545"
] | N. J. A. Sloane | 2025-11-05T15:21:39 | oeisdata/seq/A000/A000664.seq | fb239d6c877eab1a371c6ce67f2bd7ad |
A000665 | Number of 3-uniform hypergraphs on n unlabeled nodes, or equivalently number of relations with 3 arguments on n nodes. | [
"1",
"1",
"1",
"2",
"5",
"34",
"2136",
"7013320",
"1788782616656",
"53304527811667897248",
"366299663432194332594005123072",
"1171638318502989084030402509596875836036608",
"3517726593606526072882013063011594224625680712384971214848"
] | [
"nonn",
"nice"
] | 71 | 0 | 4 | [
"A000088",
"A000665",
"A006129",
"A038041",
"A092337",
"A299471",
"A301922",
"A302374",
"A302394",
"A306017",
"A306021",
"A309858",
"A320395",
"A322451"
] | [
"M1550",
"N0606"
] | N. J. A. Sloane | 2025-12-15T11:49:28 | oeisdata/seq/A000/A000665.seq | 94b61f1ef05f71b31413053342703f71 |
A000666 | Number of symmetric relations on n nodes. | [
"1",
"2",
"6",
"20",
"90",
"544",
"5096",
"79264",
"2208612",
"113743760",
"10926227136",
"1956363435360",
"652335084592096",
"405402273420996800",
"470568642161119963904",
"1023063423471189431054720",
"4178849203082023236058229792",
"32168008290073542372004082199424"
] | [
"nonn",
"nice"
] | 140 | 0 | 2 | [
"A000250",
"A000595",
"A000666",
"A001172",
"A001174",
"A006905",
"A054921"
] | [
"M1650",
"N0646"
] | N. J. A. Sloane | 2025-10-24T10:36:33 | oeisdata/seq/A000/A000666.seq | 6a5140b42a2806cfc85e9da5128d2ec9 |
A000667 | Boustrophedon transform of all-1's sequence. | [
"1",
"2",
"4",
"9",
"24",
"77",
"294",
"1309",
"6664",
"38177",
"243034",
"1701909",
"13001604",
"107601977",
"959021574",
"9157981309",
"93282431344",
"1009552482977",
"11568619292914",
"139931423833509",
"1781662223749884",
"23819069385695177",
"333601191667149054",
"... | [
"nonn",
"easy",
"nice"
] | 110 | 0 | 2 | [
"A000111",
"A000667",
"A000795",
"A002084",
"A003719",
"A009337",
"A009747",
"A109449",
"A227862",
"A292975"
] | null | N. J. A. Sloane and Simon Plouffe | 2025-11-26T15:59:31 | oeisdata/seq/A000/A000667.seq | 73d213ba002157eab6dfa842c421dd13 |
A000668 | Mersenne primes (primes of the form 2^n - 1). | [
"3",
"7",
"31",
"127",
"8191",
"131071",
"524287",
"2147483647",
"2305843009213693951",
"618970019642690137449562111",
"162259276829213363391578010288127",
"170141183460469231731687303715884105727"
] | [
"nonn",
"nice",
"hard"
] | 465 | 1 | 1 | [
"A000040",
"A000043",
"A000203",
"A000217",
"A000225",
"A000396",
"A000668",
"A001348",
"A003056",
"A007947",
"A016027",
"A019279",
"A023195",
"A023758",
"A028335",
"A034876",
"A046051",
"A057951",
"A057958",
"A059305",
"A061652",
"A083420",
"A085104",
"A124477",
"A13... | [
"M2696",
"N1080"
] | N. J. A. Sloane | 2025-12-06T16:19:17 | oeisdata/seq/A000/A000668.seq | 526d6517bb45dc5f4bbd1a5120324c82 |
A000669 | Number of series-reduced planted trees with n leaves. Also the number of essentially series series-parallel networks with n edges; also the number of essentially parallel series-parallel networks with n edges. | [
"1",
"1",
"2",
"5",
"12",
"33",
"90",
"261",
"766",
"2312",
"7068",
"21965",
"68954",
"218751",
"699534",
"2253676",
"7305788",
"23816743",
"78023602",
"256738751",
"848152864",
"2811996972",
"9353366564",
"31204088381",
"104384620070",
"350064856815",
"1176693361... | [
"nonn",
"nice",
"easy"
] | 182 | 1 | 3 | [
"A000055",
"A000084",
"A000311",
"A000669",
"A001678",
"A007827",
"A292085",
"A292086",
"A319254",
"A363064"
] | [
"M1421",
"N0558"
] | N. J. A. Sloane and John Riordan | 2025-12-29T16:19:53 | oeisdata/seq/A000/A000669.seq | 0a694a631893445c9435ec742f2d23dd |
A000670 | Fubini numbers: number of preferential arrangements of n labeled elements; or number of weak orders on n labeled elements; or number of ordered partitions of [n]. | [
"1",
"1",
"3",
"13",
"75",
"541",
"4683",
"47293",
"545835",
"7087261",
"102247563",
"1622632573",
"28091567595",
"526858348381",
"10641342970443",
"230283190977853",
"5315654681981355",
"130370767029135901",
"3385534663256845323",
"92801587319328411133",
"2677687796244384203... | [
"nonn",
"core",
"nice",
"easy"
] | 883 | 0 | 3 | [
"A000629",
"A000670",
"A002050",
"A002144",
"A002869",
"A004121",
"A004122",
"A007047",
"A007318",
"A011782",
"A019538",
"A032109",
"A034172",
"A048144",
"A052841",
"A052856",
"A053525",
"A074206",
"A076726",
"A080253",
"A080254",
"A094416",
"A131689",
"A135313",
"A15... | [
"M2952",
"N1191"
] | N. J. A. Sloane | 2026-01-02T11:57:00 | oeisdata/seq/A000/A000670.seq | 6abf2e521b20e22ebefc1df3dd129a79 |
A000671 | Number of boron trees with n nodes, i.e. n-node rooted trees with degree <= 3 at root and out-degree <= 2 elsewhere. | [
"0",
"1",
"1",
"2",
"4",
"7",
"14",
"29",
"60",
"127",
"275",
"598",
"1320",
"2936",
"6584",
"14858",
"33744",
"76999",
"176557",
"406456",
"939241",
"2177573",
"5064150",
"11809632",
"27610937",
"64705623",
"151966597",
"357623905",
"843176524",
"1991439229... | [
"nonn",
"easy",
"nice"
] | 54 | 0 | 4 | [
"A000671",
"A001190",
"A036657",
"A036658"
] | [
"M1083",
"N0411"
] | N. J. A. Sloane | 2023-05-23T21:00:24 | oeisdata/seq/A000/A000671.seq | eb4a3a33e08fce392e2ef2c0c2b60c45 |
A000672 | Number of 3-valent trees (= boron trees or binary trees) with n nodes. | [
"1",
"1",
"1",
"1",
"2",
"2",
"4",
"6",
"11",
"18",
"37",
"66",
"135",
"265",
"552",
"1132",
"2410",
"5098",
"11020",
"23846",
"52233",
"114796",
"254371",
"565734",
"1265579",
"2841632",
"6408674",
"14502229",
"32935002",
"75021750",
"171404424",
"39265... | [
"nonn",
"easy",
"nice"
] | 120 | 0 | 5 | [
"A000022",
"A000200",
"A000602",
"A000672",
"A000673",
"A000675",
"A001190",
"A052120",
"A129860",
"A144528"
] | [
"M0326",
"N0122"
] | N. J. A. Sloane | 2025-11-05T15:35:23 | oeisdata/seq/A000/A000672.seq | 1fdf486151497738566704daed25ed61 |
A000673 | Number of bicentered 3-valent (or boron, or binary) trees with n nodes. | [
"0",
"0",
"1",
"0",
"1",
"1",
"2",
"2",
"6",
"8",
"18",
"30",
"67",
"127",
"275",
"551",
"1192",
"2507",
"5475",
"11820",
"26007",
"57077",
"126686",
"281625",
"630660",
"1416116",
"3195784",
"7232624",
"16430563",
"37429146",
"85528079",
"195940960",
... | [
"nonn",
"easy",
"nice"
] | 32 | 0 | 7 | [
"A000022",
"A000200",
"A000602",
"A000672",
"A000673",
"A000675"
] | [
"M0355",
"N0133"
] | N. J. A. Sloane | 2020-12-19T03:13:00 | oeisdata/seq/A000/A000673.seq | 001e806bcb63fb54de96b51859a97f7d |
A000674 | Boustrophedon transform of 1, 2, 2, 2, 2, ... | [
"1",
"3",
"7",
"16",
"43",
"138",
"527",
"2346",
"11943",
"68418",
"435547",
"3050026",
"23300443",
"192835698",
"1718682167",
"16412205306",
"167173350543",
"1809239622978",
"20732358910387",
"250773962554186",
"3192953259262243",
"42686640718266258",
"597853508941160207... | [
"nonn"
] | 44 | 0 | 2 | [
"A000111",
"A000674",
"A040000",
"A109449"
] | null | N. J. A. Sloane, Simon Plouffe | 2025-11-10T21:50:37 | oeisdata/seq/A000/A000674.seq | 03ec40bbc7f216b72e50c0269a6c9981 |
A000675 | Number of centered 3-valent (or boron, or binary) trees with n nodes. | [
"1",
"1",
"0",
"1",
"1",
"1",
"2",
"4",
"5",
"10",
"19",
"36",
"68",
"138",
"277",
"581",
"1218",
"2591",
"5545",
"12026",
"26226",
"57719",
"127685",
"284109",
"634919",
"1425516",
"3212890",
"7269605",
"16504439",
"37592604",
"85876345",
"196717882",
... | [
"nonn",
"easy",
"nice"
] | 28 | 0 | 7 | [
"A000022",
"A000200",
"A000602",
"A000672",
"A000673",
"A000675"
] | [
"M0977",
"N0366"
] | N. J. A. Sloane | 2018-09-16T16:58:36 | oeisdata/seq/A000/A000675.seq | a42cbd5952e6d386510977bff0103292 |
A000676 | Number of centered trees with n nodes. | [
"1",
"1",
"0",
"1",
"1",
"2",
"3",
"7",
"12",
"27",
"55",
"127",
"284",
"682",
"1618",
"3979",
"9823",
"24722",
"62651",
"160744",
"415146",
"1081107",
"2831730",
"7462542",
"19764010",
"52599053",
"140580206",
"377244482",
"1016022191",
"2745783463",
"744... | [
"nonn",
"nice",
"easy"
] | 61 | 0 | 6 | [
"A000055",
"A000081",
"A000676",
"A000677",
"A027416",
"A102911"
] | [
"M0831",
"N0316"
] | N. J. A. Sloane | 2025-11-05T15:35:23 | oeisdata/seq/A000/A000676.seq | 7e36045a83348f1d80984b681cb177a8 |
A000677 | Number of bicentered trees with n nodes. | [
"0",
"0",
"1",
"0",
"1",
"1",
"3",
"4",
"11",
"20",
"51",
"108",
"267",
"619",
"1541",
"3762",
"9497",
"23907",
"61216",
"157211",
"407919",
"1063398",
"2792026",
"7365532",
"19535887",
"52037837",
"139213244",
"373820978",
"1007420841",
"2723783122",
"738... | [
"nonn",
"easy",
"nice"
] | 50 | 0 | 7 | [
"A000055",
"A000676",
"A000677"
] | [
"M2366",
"N0936"
] | N. J. A. Sloane | 2025-11-05T15:35:23 | oeisdata/seq/A000/A000677.seq | 29c4455807f336d335acc4223f656388 |
A000678 | Number of carbon (rooted) trees with n carbon atoms = unordered 4-tuples of ternary trees. | [
"0",
"1",
"1",
"2",
"4",
"9",
"18",
"42",
"96",
"229",
"549",
"1347",
"3326",
"8330",
"21000",
"53407",
"136639",
"351757",
"909962",
"2365146",
"6172068",
"16166991",
"42488077",
"112004630",
"296080425",
"784688263",
"2084521232",
"5549613097",
"14804572332"... | [
"nonn",
"easy",
"nice"
] | 37 | 0 | 4 | null | [
"M1171",
"N0448"
] | N. J. A. Sloane, E. M. Rains (rains(AT)caltech.edu) | 2018-02-09T21:45:32 | oeisdata/seq/A000/A000678.seq | 4dd8f3b21ebc60325e96c3a33e824a61 |
A000679 | Number of groups of order 2^n. | [
"1",
"1",
"2",
"5",
"14",
"51",
"267",
"2328",
"56092",
"10494213",
"49487367289"
] | [
"nonn",
"hard",
"more",
"nice"
] | 94 | 0 | 3 | [
"A000001",
"A000679",
"A046058"
] | [
"M1470",
"N0581"
] | N. J. A. Sloane | 2025-11-05T15:35:23 | oeisdata/seq/A000/A000679.seq | 241952a4d371713f9851991f370d7bd9 |
A000680 | a(n) = (2n)!/2^n. | [
"1",
"1",
"6",
"90",
"2520",
"113400",
"7484400",
"681080400",
"81729648000",
"12504636144000",
"2375880867360000",
"548828480360160000",
"151476660579404160000",
"49229914688306352000000",
"18608907752179801056000000",
"8094874872198213459360000000",
"4015057936610313875842560000000... | [
"nonn",
"easy"
] | 206 | 0 | 3 | [
"A000680",
"A001147",
"A084939",
"A084940",
"A084941",
"A084942",
"A084943",
"A084944",
"A087127",
"A089759",
"A097591",
"A132101",
"A187783",
"A241171",
"A267479",
"A267480"
] | [
"M4287",
"N1793"
] | N. J. A. Sloane | 2025-11-25T22:26:07 | oeisdata/seq/A000/A000680.seq | 9678c4165b5bf9a28129bd01ea91f188 |
A000681 | Number of n X n matrices with nonnegative entries and every row and column sum 2. | [
"1",
"1",
"3",
"21",
"282",
"6210",
"202410",
"9135630",
"545007960",
"41514583320",
"3930730108200",
"452785322266200",
"62347376347779600",
"10112899541133589200",
"1908371363842760216400",
"414517594539154672566000",
"102681435747106627787376000",
"28772944645196614863048048000"... | [
"nonn",
"nice",
"easy"
] | 123 | 0 | 3 | [
"A000142",
"A000681",
"A001499",
"A001500",
"A005650",
"A123544",
"A172806",
"A172862",
"A172894",
"A172919",
"A172944",
"A172958",
"A257493",
"A269742",
"A307804"
] | [
"M3084",
"N1250"
] | N. J. A. Sloane, Simon Plouffe | 2025-11-05T15:35:23 | oeisdata/seq/A000/A000681.seq | 4b126eb951f9b5b0e09239fee2327b50 |
A000682 | Semi-meanders: number of ways a semi-infinite directed curve can cross a straight line n times. | [
"1",
"1",
"2",
"4",
"10",
"24",
"66",
"174",
"504",
"1406",
"4210",
"12198",
"37378",
"111278",
"346846",
"1053874",
"3328188",
"10274466",
"32786630",
"102511418",
"329903058",
"1042277722",
"3377919260",
"10765024432",
"35095839848",
"112670468128",
"36919270255... | [
"nonn",
"nice"
] | 216 | 1 | 3 | [
"A000136",
"A000560",
"A000682",
"A001011",
"A001997",
"A086441",
"A259689"
] | [
"M1205",
"N0464"
] | N. J. A. Sloane | 2025-11-05T15:21:39 | oeisdata/seq/A000/A000682.seq | 868bff225fdaa9dc0698153880e7500f |
A000683 | Number of colorings of labeled graphs on n nodes using exactly 2 colors, divided by 4. | [
"0",
"1",
"6",
"40",
"360",
"4576",
"82656",
"2122240",
"77366400",
"4002843136",
"293717546496",
"30558458490880",
"4505780560619520",
"941417163728674816",
"278628902101315608576",
"116805328001281573519360",
"69340603828363322892779520",
"58287619305053298399714082816",
"69366... | [
"nonn",
"nice",
"easy"
] | 44 | 1 | 3 | [
"A000683",
"A047863",
"A058843",
"A213441"
] | [
"M4238",
"N1770"
] | N. J. A. Sloane | 2025-05-11T01:05:41 | oeisdata/seq/A000/A000683.seq | 6f59bc57077acbf4320c4d11275a6f67 |
A000684 | Number of colored labeled n-node graphs with 2 interchangeable colors. | [
"1",
"3",
"13",
"81",
"721",
"9153",
"165313",
"4244481",
"154732801",
"8005686273",
"587435092993",
"61116916981761",
"9011561121239041",
"1882834327457349633",
"557257804202631217153",
"233610656002563147038721",
"138681207656726645785559041"
] | [
"nonn",
"nice",
"easy"
] | 73 | 1 | 2 | [
"A000683",
"A000684",
"A058872",
"A111636",
"A134531"
] | [
"M2954",
"N1192"
] | N. J. A. Sloane | 2023-10-27T18:25:40 | oeisdata/seq/A000/A000684.seq | 78d378572d4d47be50e7e36740a25bde |
A000685 | Number of 3-colored labeled graphs on n nodes, divided by 3. | [
"1",
"5",
"41",
"545",
"11681",
"402305",
"22207361",
"1961396225",
"276825510401",
"62368881977345",
"22413909724518401",
"12840603873823473665",
"11720394922432296755201",
"17037597932370037286600705"
] | [
"nonn",
"easy",
"nice"
] | 42 | 1 | 2 | [
"A000683",
"A000685",
"A047863",
"A191371",
"A223887"
] | [
"M3995",
"N1656"
] | N. J. A. Sloane | 2025-05-10T23:14:28 | oeisdata/seq/A000/A000685.seq | f74c087085f66e65d2c59759d7d70cf5 |
A000686 | Number of 4-colored labeled graphs on n nodes, divided by 4. | [
"1",
"7",
"85",
"1777",
"63601",
"3882817",
"403308865",
"71139019777",
"21276992674561",
"10778161937857537",
"9238819435213784065",
"13390649605615389843457",
"32796747486424209782108161",
"135669064080920007649863745537",
"947468281528010179181982467702785",
"11166618111585805201637... | [
"nonn",
"easy",
"nice"
] | 52 | 1 | 2 | [
"A000683",
"A000685",
"A000686",
"A223887"
] | [
"M4449",
"N1884"
] | N. J. A. Sloane | 2025-05-10T23:14:24 | oeisdata/seq/A000/A000686.seq | a4ee728cee225baf47cf0f473039b9be |
A000687 | Boustrophedon transform (first version) of Fibonacci numbers 0,1,1,2,3,5,... | [
"1",
"1",
"2",
"6",
"17",
"59",
"229",
"1029",
"5242",
"30040",
"191201",
"1338897",
"10228097",
"84647981",
"754437958",
"7204350870",
"73382899597",
"794189092567",
"9100736472725",
"110080467183393",
"1401588037032782",
"18737851806495008",
"262435512896178877"
] | [
"nonn"
] | 42 | 0 | 3 | [
"A000045",
"A000687",
"A000738",
"A000744",
"A092073"
] | null | N. J. A. Sloane and Simon Plouffe | 2024-05-04T05:31:52 | oeisdata/seq/A000/A000687.seq | 8289f92911b1f89a77d2f035d91c981a |
A000688 | Number of Abelian groups of order n; number of factorizations of n into prime powers. | [
"1",
"1",
"1",
"2",
"1",
"1",
"1",
"3",
"2",
"1",
"1",
"2",
"1",
"1",
"1",
"5",
"1",
"2",
"1",
"2",
"1",
"1",
"1",
"3",
"2",
"1",
"3",
"2",
"1",
"1",
"1",
"7",
"1",
"1",
"1",
"4",
"1",
"1",
"1",
"3",
"1",
"1",
"1",
"2",
"2",
"... | [
"nonn",
"core",
"easy",
"nice",
"mult"
] | 205 | 1 | 4 | [
"A000001",
"A000041",
"A000688",
"A000961",
"A001055",
"A005361",
"A021002",
"A034382",
"A046054",
"A046055",
"A046056",
"A046101",
"A050360",
"A050361",
"A051532",
"A055653",
"A057521",
"A060689",
"A080729",
"A101872",
"A101876",
"A124010",
"A129667",
"A188585",
"A36... | [
"M0064",
"N0020"
] | N. J. A. Sloane | 2025-12-15T13:19:49 | oeisdata/seq/A000/A000688.seq | 732978ac4c852ee33cfc3ec53d368d92 |
A000689 | Final decimal digit of 2^n. | [
"1",
"2",
"4",
"8",
"6",
"2",
"4",
"8",
"6",
"2",
"4",
"8",
"6",
"2",
"4",
"8",
"6",
"2",
"4",
"8",
"6",
"2",
"4",
"8",
"6",
"2",
"4",
"8",
"6",
"2",
"4",
"8",
"6",
"2",
"4",
"8",
"6",
"2",
"4",
"8",
"6",
"2",
"4",
"8",
"6",
"... | [
"nonn",
"base",
"easy"
] | 88 | 0 | 2 | [
"A000079",
"A000689",
"A000855",
"A008952",
"A034887",
"A173635"
] | null | N. J. A. Sloane | 2025-08-14T06:02:40 | oeisdata/seq/A000/A000689.seq | 63edba27fdd4f52d9a3f21bcff9f808c |
A000690 | Landau's approximation to population of x^2 + y^2 <= 2^n. | [
"1",
"2",
"3",
"4",
"7",
"13",
"24",
"44",
"83",
"157",
"297",
"567",
"1085",
"2086",
"4019",
"7766",
"15039",
"29181",
"56717",
"110408",
"215225",
"420076",
"820836",
"1605587",
"3143562",
"6160098",
"12080946",
"23710229",
"46565965",
"91512121",
"17994... | [
"nonn"
] | 32 | 0 | 2 | [
"A000050",
"A000690",
"A064533"
] | [
"M0586",
"N0212"
] | N. J. A. Sloane | 2022-05-13T18:49:36 | oeisdata/seq/A000/A000690.seq | 2fef4c1c29eec5093ebda18c65356884 |
A000691 | Ramanujan's approximation to population of x^2 + y^2 <= 2^n. | [
"1",
"2",
"3",
"5",
"9",
"16",
"29",
"52",
"94",
"175",
"327",
"616",
"1169",
"2231",
"4273",
"8215",
"15842",
"30628",
"59345",
"115208",
"224040",
"436343",
"850981",
"1661663",
"3248231",
"6356076",
"12448925",
"24402959",
"47873156",
"93984236",
"18463... | [
"nonn"
] | 35 | 0 | 2 | [
"A000050",
"A000690",
"A000691",
"A000692",
"A064533"
] | [
"M0713",
"N0263"
] | N. J. A. Sloane | 2022-05-23T09:11:53 | oeisdata/seq/A000/A000691.seq | f4aa0efbc5cf41c07205251c55f7a846 |
A000692 | An approximation to population of x^2 + y^2 <= 2^n. | [
"1",
"3",
"4",
"5",
"9",
"15",
"27",
"50",
"92",
"171",
"322",
"610",
"1161",
"2220",
"4260",
"8201",
"15828",
"30622",
"59362",
"115287",
"224260",
"436871",
"852161",
"1664196",
"3253531",
"6366973",
"12471056",
"24447507",
"47962236",
"94161474",
"18498... | [
"nonn"
] | 40 | 0 | 2 | [
"A000050",
"A000690",
"A000691",
"A000692",
"A064533"
] | [
"M2311",
"N0913"
] | N. J. A. Sloane | 2023-08-06T23:33:59 | oeisdata/seq/A000/A000692.seq | 452ab50dfceeffe1c100c8e7423612e0 |
A000693 | Related to population of numbers of form x^2 + y^2. | [
"1",
"2",
"3",
"6",
"10",
"19",
"35",
"62",
"118",
"219",
"414",
"783",
"1497",
"2860",
"5503",
"10593",
"20471",
"39637",
"76918",
"149501",
"291115",
"567581",
"1108022",
"2165621",
"4237085",
"8297727",
"16264207",
"31904254",
"62630372",
"123031586",
"... | [
"nonn"
] | 21 | 1 | 2 | null | [
"M0767",
"N0292"
] | N. J. A. Sloane | 2022-02-01T01:09:59 | oeisdata/seq/A000/A000693.seq | 248c6480f647e6a7b56c02f8566c2522 |
A000694 | Related to population of numbers of form x^2 + y^2. | [
"1",
"2",
"4",
"6",
"11",
"19",
"34",
"63",
"117",
"218",
"411",
"780",
"1487",
"2849",
"5477",
"10562",
"20419",
"39563",
"76805",
"149360",
"290896",
"567321",
"1107775",
"2165487",
"4237384",
"8299283",
"16268639",
"31915437",
"62656158",
"123088460",
"... | [
"nonn"
] | 22 | 1 | 2 | [
"A000691",
"A000694"
] | [
"M1021",
"N0384"
] | N. J. A. Sloane | 2014-03-15T05:14:52 | oeisdata/seq/A000/A000694.seq | 0d4d966c7f5e8c0702039095eba95b85 |
A000695 | Moser-de Bruijn sequence: sums of distinct powers of 4. | [
"0",
"1",
"4",
"5",
"16",
"17",
"20",
"21",
"64",
"65",
"68",
"69",
"80",
"81",
"84",
"85",
"256",
"257",
"260",
"261",
"272",
"273",
"276",
"277",
"320",
"321",
"324",
"325",
"336",
"337",
"340",
"341",
"1024",
"1025",
"1028",
"1029",
"1040",
... | [
"nonn",
"nice",
"easy"
] | 332 | 0 | 3 | [
"A000012",
"A000027",
"A000225",
"A000302",
"A000695",
"A001196",
"A001316",
"A001511",
"A005836",
"A007088",
"A007583",
"A033042",
"A033052",
"A039966",
"A048720",
"A048723",
"A048883",
"A059884",
"A059901",
"A059904",
"A059905",
"A059906",
"A062880",
"A102376",
"A10... | [
"M3259",
"N1315"
] | N. J. A. Sloane | 2025-11-05T15:35:23 | oeisdata/seq/A000/A000695.seq | b9e36705af1159652f6a6103fa7a261f |
A000696 | Numbers k such that (1,k) is "good". | [
"1",
"7",
"31",
"37",
"109",
"121",
"127",
"133",
"151",
"157",
"403",
"421",
"511",
"529",
"631",
"637",
"661",
"679",
"1579",
"1621",
"1633",
"1969",
"1981",
"2017",
"2041",
"2047",
"2053",
"2071",
"2077",
"2143",
"2149",
"2167",
"2173",
"2401",
... | [
"nonn",
"base"
] | 25 | 1 | 2 | [
"A000695",
"A000696"
] | [
"M4397",
"N1853"
] | N. J. A. Sloane | 2022-02-02T03:57:58 | oeisdata/seq/A000/A000696.seq | 8a131e81ffa71ca89b241b8eae42a052 |
A000697 | Boustrophedon transform of 1, 1, 4, 9, 16, ... | [
"1",
"2",
"7",
"26",
"89",
"316",
"1243",
"5564",
"28321",
"162160",
"1032051",
"7226636",
"55206161",
"456886912",
"4072080587",
"38885496092",
"396084390849",
"4286637591872",
"49121248360291",
"594159600856332",
"7565074996215025",
"101137602761945440"
] | [
"nonn"
] | 52 | 0 | 2 | [
"A000290",
"A000697",
"A000745",
"A109449"
] | null | N. J. A. Sloane, Simon Plouffe | 2025-11-10T21:50:37 | oeisdata/seq/A000/A000697.seq | 2c47227b4b5df05548d636c5b4a28d81 |
A000698 | A problem of configurations: a(0) = 1; for n>0, a(n) = (2n-1)!! - Sum_{k=1..n-1} (2k-1)!! a(n-k). Also the number of shellings of an n-cube, divided by 2^n n!. | [
"1",
"1",
"2",
"10",
"74",
"706",
"8162",
"110410",
"1708394",
"29752066",
"576037442",
"12277827850",
"285764591114",
"7213364729026",
"196316804255522",
"5731249477826890",
"178676789473121834",
"5925085744543837186",
"208256802758892355202",
"7734158085942678174730"
] | [
"nonn",
"easy",
"nice"
] | 283 | 0 | 3 | [
"A000165",
"A000168",
"A000260",
"A000309",
"A000698",
"A000699",
"A001147",
"A002005",
"A004208",
"A005411",
"A005412",
"A053979",
"A062980",
"A115974",
"A167872",
"A258219",
"A258222",
"A267827",
"A322398"
] | [
"M1974",
"N0783"
] | N. J. A. Sloane, Richard Ehrenborg, Gabor Hetyei | 2025-11-05T15:21:39 | oeisdata/seq/A000/A000698.seq | af9b5e6f4a1d5220d68a4dabd0084a1b |
A000699 | Number of irreducible chord diagrams with 2n nodes. | [
"1",
"1",
"1",
"4",
"27",
"248",
"2830",
"38232",
"593859",
"10401712",
"202601898",
"4342263000",
"101551822350",
"2573779506192",
"70282204726396",
"2057490936366320",
"64291032462761955",
"2136017303903513184",
"75197869250518812754",
"2796475872605709079512",
"10954971452... | [
"nonn",
"easy",
"nice"
] | 233 | 0 | 4 | [
"A000168",
"A000260",
"A000309",
"A000698",
"A000699",
"A002005",
"A004300",
"A007297",
"A016098",
"A051862",
"A062980",
"A099947",
"A136653",
"A212273",
"A232223",
"A267827",
"A268815",
"A306438",
"A322402",
"A324166",
"A324172",
"A324173",
"A324327"
] | [
"M3618",
"N1468"
] | N. J. A. Sloane | 2025-11-05T15:21:39 | oeisdata/seq/A000/A000699.seq | 3d9622d5bab8a076848e555a29bcc2c7 |
A000700 | Expansion of Product_{k>=0} (1 + x^(2k+1)); number of partitions of n into distinct odd parts; number of self-conjugate partitions; number of symmetric Ferrers graphs with n nodes. | [
"1",
"1",
"0",
"1",
"1",
"1",
"1",
"1",
"2",
"2",
"2",
"2",
"3",
"3",
"3",
"4",
"5",
"5",
"5",
"6",
"7",
"8",
"8",
"9",
"11",
"12",
"12",
"14",
"16",
"17",
"18",
"20",
"23",
"25",
"26",
"29",
"33",
"35",
"37",
"41",
"46",
"49",
"52"... | [
"nonn",
"easy",
"nice"
] | 304 | 0 | 9 | [
"A000009",
"A000041",
"A000700",
"A000701",
"A046682",
"A052002",
"A053250",
"A069910",
"A069911",
"A081362",
"A085547",
"A088994",
"A146061",
"A169987",
"A169995",
"A218907",
"A295291",
"A304044"
] | [
"M0217",
"N0078"
] | N. J. A. Sloane | 2025-11-05T15:21:39 | oeisdata/seq/A000/A000700.seq | b2389905201dd83e185fca49ef27ec34 |
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