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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
A001501 | Number of n X n 0-1 matrices with all column and row sums equal to 3. | [
"1",
"0",
"0",
"1",
"24",
"2040",
"297200",
"68938800",
"24046189440",
"12025780892160",
"8302816499443200",
"7673688777463632000",
"9254768770160124288000",
"14255616537578735986867200",
"27537152449960680597739468800",
"65662040698002721810659005184000"
] | [
"nonn",
"nice"
] | 78 | 0 | 5 | [
"A001499",
"A001501",
"A008300",
"A284990"
] | [
"M5175",
"N2247"
] | N. J. A. Sloane | 2023-10-27T19:26:21 | oeisdata/seq/A001/A001501.seq | d322dbad3018e704ddc21d8976d52290 |
A001502 | Largest number requiring n syllables in English (U.S.) - not well-defined, but the next term may be twelve millillion, too large to write down here. | [
"12",
"90",
"12000000000000"
] | [
"word",
"nonn",
"bref"
] | 8 | 1 | 1 | null | null | N. J. A. Sloane | 2022-02-01T23:42:02 | oeisdata/seq/A001/A001502.seq | fa91ca63c3570df7136d6c6a3db417d0 |
A001503 | Largest number requiring n syllables in English (U.K.) - not well-defined, but the next term may be twelve millillion, too large to write down here. | [
"12",
"90",
"12000000000000000000"
] | [
"word",
"nonn",
"bref"
] | 8 | 1 | 1 | null | null | N. J. A. Sloane | 2022-02-01T23:42:17 | oeisdata/seq/A001/A001503.seq | 3e76e68bed18c5608d9aff9b5ec75f14 |
A001504 | a(n) = (3*n+1)*(3*n+2). | [
"2",
"20",
"56",
"110",
"182",
"272",
"380",
"506",
"650",
"812",
"992",
"1190",
"1406",
"1640",
"1892",
"2162",
"2450",
"2756",
"3080",
"3422",
"3782",
"4160",
"4556",
"4970",
"5402",
"5852",
"6320",
"6806",
"7310",
"7832",
"8372",
"8930",
"9506",
"... | [
"nonn",
"easy"
] | 91 | 0 | 1 | [
"A001504",
"A002378",
"A016777",
"A016789",
"A060544",
"A073010",
"A144410",
"A387235"
] | null | N. J. A. Sloane | 2025-09-08T22:40:48 | oeisdata/seq/A001/A001504.seq | f7d5e0db3aea7ad451cadc0d9eb4e875 |
A001505 | a(n) = (4*n+1)*(4*n+2)*(4*n+3). | [
"6",
"210",
"990",
"2730",
"5814",
"10626",
"17550",
"26970",
"39270",
"54834",
"74046",
"97290",
"124950",
"157410",
"195054",
"238266",
"287430",
"342930",
"405150",
"474474",
"551286",
"635970",
"728910",
"830490",
"941094",
"1061106",
"1190910",
"1330890",
... | [
"nonn",
"easy"
] | 55 | 0 | 1 | [
"A001505",
"A004767",
"A008586",
"A015219",
"A054777",
"A157870"
] | null | N. J. A. Sloane | 2025-09-09T08:13:01 | oeisdata/seq/A001/A001505.seq | 1973d7aefa6f5d8635da0c2ae1c271ab |
A001506 | a(n) is the number of c-nets with n+1 vertices and 2n edges, n >= 1. | [
"0",
"0",
"1",
"4",
"24",
"188",
"1705",
"16980",
"180670",
"2020120",
"23478426",
"281481880",
"3461873536",
"43494961404",
"556461656569",
"7230987646484",
"95244774132810",
"1269534571172912",
"17100621281619328",
"232511930087682528",
"3188042426888493288"
] | [
"nonn"
] | 40 | 1 | 4 | [
"A001506",
"A290326"
] | [
"M3603",
"N1462"
] | N. J. A. Sloane | 2017-07-28T09:38:40 | oeisdata/seq/A001/A001506.seq | a3a72a9204da6798479755f16b54c737 |
A001507 | a(n) is the number of c-nets with n+1 vertices and 2n+1 edges, n >= 1. | [
"0",
"0",
"0",
"3",
"33",
"338",
"3580",
"39525",
"452865",
"5354832",
"65022840",
"807560625",
"10224817515",
"131631305718",
"1719292293940",
"22743461653913",
"304256251541865",
"4111134671255120",
"56049154766899216",
"770325744569310630",
"10664613057653024586",
"14862... | [
"nonn"
] | 39 | 1 | 4 | [
"A001507",
"A290326"
] | [
"M3132",
"N1270"
] | N. J. A. Sloane | 2017-07-28T09:38:08 | oeisdata/seq/A001/A001507.seq | 9a11887c875f2ebf109d20b19a8f6a61 |
A001508 | a(n) is the number of c-nets with n+1 vertices and 2n+2 edges, n >= 1. | [
"0",
"0",
"0",
"0",
"13",
"252",
"3740",
"51300",
"685419",
"9095856",
"120872850",
"1614234960",
"21697730835",
"293695935764",
"4003423965684",
"54944523689692",
"758990230992175",
"10548884795729280",
"147458773053913268",
"2072369440050644208",
"29271357456284966994"
] | [
"nonn"
] | 37 | 1 | 5 | [
"A001508",
"A290326"
] | [
"M4918",
"N2111"
] | N. J. A. Sloane | 2017-07-28T09:38:50 | oeisdata/seq/A001/A001508.seq | 5d34ba371aceecf02bb3ac2adb77c4b9 |
A001509 | a(n) = (5*n + 1)*(5*n + 2)*(5*n + 3). | [
"6",
"336",
"1716",
"4896",
"10626",
"19656",
"32736",
"50616",
"74046",
"103776",
"140556",
"185136",
"238266",
"300696",
"373176",
"456456",
"551286",
"658416",
"778596",
"912576",
"1061106",
"1224936",
"1404816",
"1601496",
"1815726",
"2048256",
"2299836",
"2... | [
"nonn",
"easy"
] | 35 | 0 | 1 | [
"A001509",
"A001622",
"A016861",
"A016873",
"A016885"
] | null | N. J. A. Sloane, Dec 11 1996 | 2025-09-07T16:15:53 | oeisdata/seq/A001/A001509.seq | 5fbc72521028ef3148f1a70a71f52bc2 |
A001510 | a(n) = 2*a(n-1)*(a(n-1)-1) for n > 1, with a(0) = 1, a(1) = 2. | [
"1",
"2",
"4",
"24",
"1104",
"2435424",
"11862575248704",
"281441383062305809756861824",
"158418504200047111075388369241884118003210485743490304",
"50192844945960688344377119996413128352439813841590950757549699306732809442403485652017560973684452797044224"
] | [
"nonn",
"nice",
"changed"
] | 47 | 0 | 2 | [
"A000032",
"A001510",
"A001566",
"A001622",
"A002715"
] | [
"M1301",
"N0499"
] | N. J. A. Sloane | 2026-01-08T02:56:40 | oeisdata/seq/A001/A001510.seq | e7d52b8f3861f57f288122d1c0223ec0 |
A001511 | The ruler function: exponent of the highest power of 2 dividing 2n. Equivalently, the 2-adic valuation of 2n. | [
"1",
"2",
"1",
"3",
"1",
"2",
"1",
"4",
"1",
"2",
"1",
"3",
"1",
"2",
"1",
"5",
"1",
"2",
"1",
"3",
"1",
"2",
"1",
"4",
"1",
"2",
"1",
"3",
"1",
"2",
"1",
"6",
"1",
"2",
"1",
"3",
"1",
"2",
"1",
"4",
"1",
"2",
"1",
"3",
"1",
"... | [
"mult",
"nonn",
"nice",
"easy",
"core",
"hear",
"changed"
] | 608 | 1 | 2 | [
"A000005",
"A000041",
"A000079",
"A001511",
"A002487",
"A003188",
"A003278",
"A003602",
"A005187",
"A007814",
"A007949",
"A018238",
"A035263",
"A047999",
"A050600",
"A050603",
"A050604",
"A051064",
"A051731",
"A054525",
"A054852",
"A055457",
"A065176",
"A067029",
"A08... | [
"M0127",
"N0051"
] | N. J. A. Sloane | 2026-01-04T23:11:20 | oeisdata/seq/A001/A001511.seq | 5554a9daed16e35f95d9a1f6b6cf0338 |
A001512 | a(n) = (5*n+1)*(5*n+2)*(5*n+3)*(5*n+4). | [
"24",
"3024",
"24024",
"93024",
"255024",
"570024",
"1113024",
"1974024",
"3258024",
"5085024",
"7590024",
"10923024",
"15249024",
"20748024",
"27615024",
"36060024",
"46308024",
"58599024",
"73188024",
"90345024",
"110355024",
"133518024",
"160149024",
"190578024",
"... | [
"nonn",
"easy"
] | 35 | 0 | 1 | [
"A001512",
"A001622",
"A151989"
] | null | N. J. A. Sloane | 2025-11-27T12:50:11 | oeisdata/seq/A001/A001512.seq | 768cd1339f2c8905bf935a445b68ec6f |
A001513 | a(n) = (6*n+1)*(6*n+5). | [
"5",
"77",
"221",
"437",
"725",
"1085",
"1517",
"2021",
"2597",
"3245",
"3965",
"4757",
"5621",
"6557",
"7565",
"8645",
"9797",
"11021",
"12317",
"13685",
"15125",
"16637",
"18221",
"19877",
"21605",
"23405",
"25277",
"27221",
"29237",
"31325",
"33485",
... | [
"nonn",
"easy"
] | 36 | 0 | 1 | [
"A001513",
"A016921",
"A016969"
] | null | N. J. A. Sloane | 2025-12-10T13:42:05 | oeisdata/seq/A001/A001513.seq | b393904408f67b2907b2116d45786264 |
A001514 | Bessel polynomial {y_n}'(1). | [
"0",
"1",
"9",
"81",
"835",
"9990",
"137466",
"2148139",
"37662381",
"733015845",
"15693217705",
"366695853876",
"9289111077324",
"253623142901401",
"7425873460633005",
"232122372003909045",
"7715943399320562331",
"271796943164015920914",
"10114041937573463433966"
] | [
"nonn"
] | 37 | 0 | 3 | [
"A001514",
"A001515",
"A001516",
"A001518",
"A065920",
"A144505"
] | [
"M4654",
"N1993"
] | N. J. A. Sloane | 2020-02-16T10:51:08 | oeisdata/seq/A001/A001514.seq | db341dd94bed26c3203f25dc123f18e9 |
A001515 | Bessel polynomial y_n(x) evaluated at x=1. | [
"1",
"2",
"7",
"37",
"266",
"2431",
"27007",
"353522",
"5329837",
"90960751",
"1733584106",
"36496226977",
"841146804577",
"21065166341402",
"569600638022431",
"16539483668991901",
"513293594376771362",
"16955228098102446847",
"593946277027962411007",
"21992967478132711654106",... | [
"nonn",
"easy",
"nice"
] | 184 | 0 | 2 | [
"A000108",
"A000806",
"A001497",
"A001498",
"A001514",
"A001515",
"A001517",
"A105748",
"A105749",
"A143990",
"A144301",
"A144416",
"A144498",
"A144505",
"A144506",
"A144507",
"A144508",
"A144509",
"A144513",
"A144514",
"A149187",
"A281358",
"A281359",
"A281360",
"A28... | [
"M1803",
"N0713"
] | N. J. A. Sloane | 2025-12-21T17:38:28 | oeisdata/seq/A001/A001515.seq | f19e9f71193b5cd48f9a3b9660e87231 |
A001516 | Bessel polynomial {y_n}''(1). | [
"0",
"0",
"6",
"120",
"1980",
"32970",
"584430",
"11204676",
"233098740",
"5254404210",
"127921380840",
"3350718545460",
"94062457204716",
"2819367702529560",
"89912640142178490",
"3040986592542420060",
"108752084073199561140",
"4101112025363285051526",
"162673458993269290828530"... | [
"nonn",
"easy"
] | 43 | 0 | 3 | [
"A001497",
"A001498",
"A001514",
"A001515",
"A001516",
"A001518",
"A065944",
"A144505"
] | [
"M4295",
"N1795"
] | N. J. A. Sloane | 2025-09-11T05:13:52 | oeisdata/seq/A001/A001516.seq | e308475713b9c3303af2353e87806123 |
A001517 | Bessel polynomials y_n(x) (see A001498) evaluated at 2. | [
"1",
"3",
"19",
"193",
"2721",
"49171",
"1084483",
"28245729",
"848456353",
"28875761731",
"1098127402131",
"46150226651233",
"2124008553358849",
"106246577894593683",
"5739439214861417731",
"332993721039856822081",
"20651350143685984386753"
] | [
"nonn",
"easy",
"nice",
"changed"
] | 117 | 0 | 2 | [
"A001515",
"A001517",
"A001518",
"A002119",
"A053556",
"A053557",
"A080893",
"A099022",
"A105747",
"A243593"
] | [
"M3062",
"N1240"
] | N. J. A. Sloane | 2026-01-13T08:14:07 | oeisdata/seq/A001/A001517.seq | 57a89e2aee20148607966151703bc904 |
A001518 | Bessel polynomial y_n(3). | [
"1",
"4",
"37",
"559",
"11776",
"318511",
"10522639",
"410701432",
"18492087079",
"943507142461",
"53798399207356",
"3390242657205889",
"233980541746413697",
"17551930873638233164",
"1421940381306443299981",
"123726365104534205331511",
"11507973895102987539130504"
] | [
"nonn",
"easy"
] | 87 | 0 | 2 | [
"A001498",
"A001515",
"A001517",
"A001518"
] | [
"M3669",
"N1495"
] | N. J. A. Sloane | 2025-12-12T09:02:11 | oeisdata/seq/A001/A001518.seq | 7fce0d73b2f82274e89f256c5f34f1b1 |
A001519 | a(n) = 3*a(n-1) - a(n-2) for n >= 2, with a(0) = a(1) = 1. | [
"1",
"1",
"2",
"5",
"13",
"34",
"89",
"233",
"610",
"1597",
"4181",
"10946",
"28657",
"75025",
"196418",
"514229",
"1346269",
"3524578",
"9227465",
"24157817",
"63245986",
"165580141",
"433494437",
"1134903170",
"2971215073",
"7778742049",
"20365011074",
"533162... | [
"nonn",
"nice",
"easy",
"core"
] | 893 | 0 | 3 | [
"A000045",
"A001519",
"A001622",
"A001653",
"A001654",
"A001906",
"A002559",
"A055105",
"A055106",
"A055107",
"A060920",
"A074664",
"A082582",
"A094954",
"A101368",
"A104457",
"A122367",
"A124292",
"A124293",
"A124294",
"A124295",
"A130255",
"A130256",
"A140068",
"A14... | [
"M1439",
"N0569"
] | N. J. A. Sloane | 2025-12-11T12:35:38 | oeisdata/seq/A001/A001519.seq | f0c6502c5355587f59224fe14087a5fd |
A001520 | a(n) = (6*n+1)*(6*n+3)*(6*n+5). | [
"15",
"693",
"3315",
"9177",
"19575",
"35805",
"59163",
"90945",
"132447",
"184965",
"249795",
"328233",
"421575",
"531117",
"658155",
"803985",
"969903",
"1157205",
"1367187",
"1601145",
"1860375",
"2146173",
"2459835",
"2802657",
"3175935",
"3580965",
"4019043",... | [
"nonn",
"easy"
] | 27 | 0 | 1 | null | null | N. J. A. Sloane | 2025-07-21T16:16:37 | oeisdata/seq/A001/A001520.seq | e66ab16ad3f9d2746a86cdd765a62c78 |
A001521 | a(1) = 1; thereafter a(n+1) = floor(sqrt(2*a(n)*(a(n)+1))). | [
"1",
"2",
"3",
"4",
"6",
"9",
"13",
"19",
"27",
"38",
"54",
"77",
"109",
"154",
"218",
"309",
"437",
"618",
"874",
"1236",
"1748",
"2472",
"3496",
"4944",
"6992",
"9888",
"13984",
"19777",
"27969",
"39554",
"55938",
"79108",
"111876",
"158217",
"22... | [
"nonn",
"nice",
"easy"
] | 100 | 1 | 2 | [
"A000196",
"A001521",
"A017911",
"A190660",
"A241576"
] | [
"M0569",
"N0206"
] | N. J. A. Sloane | 2025-11-05T15:35:23 | oeisdata/seq/A001/A001521.seq | 01046460f20f93f98ea50acce6bb8be8 |
A001522 | Number of n-stacks with strictly receding walls, or the number of Type A partitions of n in the sense of Auluck (1951). | [
"1",
"1",
"1",
"1",
"2",
"3",
"5",
"7",
"10",
"14",
"19",
"26",
"35",
"47",
"62",
"82",
"107",
"139",
"179",
"230",
"293",
"372",
"470",
"591",
"740",
"924",
"1148",
"1422",
"1756",
"2161",
"2651",
"3244",
"3957",
"4815",
"5844",
"7075",
"8545"... | [
"nonn",
"easy",
"nice"
] | 137 | 0 | 5 | [
"A000041",
"A000166",
"A000700",
"A001522",
"A001523",
"A001524",
"A002467",
"A003242",
"A008292",
"A059776",
"A064391",
"A064410",
"A064428",
"A088902",
"A114088",
"A114921",
"A115720",
"A115994",
"A118199",
"A238351",
"A238352",
"A238394",
"A238395",
"A257989",
"A32... | [
"M0644",
"N0238"
] | N. J. A. Sloane | 2025-11-05T15:21:40 | oeisdata/seq/A001/A001522.seq | d333114e1dc91918feb8610be7ff886c |
A001523 | Number of stacks, or planar partitions of n; also weakly unimodal compositions of n. | [
"1",
"1",
"2",
"4",
"8",
"15",
"27",
"47",
"79",
"130",
"209",
"330",
"512",
"784",
"1183",
"1765",
"2604",
"3804",
"5504",
"7898",
"11240",
"15880",
"22277",
"31048",
"43003",
"59220",
"81098",
"110484",
"149769",
"202070",
"271404",
"362974",
"483439... | [
"nonn",
"nice",
"easy"
] | 130 | 0 | 3 | [
"A000569",
"A001522",
"A001523",
"A001524",
"A007052",
"A054250",
"A059204",
"A059618",
"A059623",
"A072704",
"A072706",
"A100505",
"A100506",
"A107429",
"A115981",
"A156253",
"A227038",
"A247255",
"A328509",
"A329398",
"A332280",
"A332282",
"A332283",
"A332285",
"A33... | [
"M1102",
"N0420"
] | N. J. A. Sloane | 2025-11-05T15:21:40 | oeisdata/seq/A001/A001523.seq | 82a73016d89d432181d20569d290b46e |
A001524 | Number of stacks, or arrangements of n pennies in contiguous rows, each touching 2 in row below. | [
"1",
"1",
"1",
"2",
"3",
"5",
"8",
"12",
"18",
"26",
"38",
"53",
"75",
"103",
"142",
"192",
"260",
"346",
"461",
"607",
"797",
"1038",
"1348",
"1738",
"2234",
"2856",
"3638",
"4614",
"5832",
"7342",
"9214",
"11525",
"14369",
"17863",
"22142",
"27... | [
"nonn",
"nice",
"easy"
] | 97 | 0 | 4 | [
"A001522",
"A001523",
"A001524",
"A007293",
"A015128",
"A171604",
"A259095"
] | [
"M0687",
"N0253"
] | N. J. A. Sloane | 2025-11-05T15:35:23 | oeisdata/seq/A001/A001524.seq | 2cefa026cd7b824c82a7e2b3bfbb6f90 |
A001525 | a(n) = (3n)!/(3!n!). | [
"1",
"60",
"10080",
"3326400",
"1816214400",
"1482030950400",
"1689515283456000",
"2564684200286208000",
"5001134190558105600000",
"12182762888199545241600000",
"36255902355281846639001600000",
"129433571408356192501235712000000",
"545950804200446419970212233216000000"
] | [
"nonn"
] | 25 | 1 | 2 | [
"A001525",
"A064350",
"A157704",
"A157705"
] | [
"M5320"
] | N. J. A. Sloane | 2022-02-02T04:00:45 | oeisdata/seq/A001/A001525.seq | 3dbd0559d8cb3fe4087b0cad86e0c5f7 |
A001526 | a(n) = (7*n+1)*(7*n+6). | [
"6",
"104",
"300",
"594",
"986",
"1476",
"2064",
"2750",
"3534",
"4416",
"5396",
"6474",
"7650",
"8924",
"10296",
"11766",
"13334",
"15000",
"16764",
"18626",
"20586",
"22644",
"24800",
"27054",
"29406",
"31856",
"34404",
"37050",
"39794",
"42636",
"45576"... | [
"nonn",
"easy"
] | 32 | 0 | 1 | [
"A001526",
"A016993",
"A017053"
] | null | N. J. A. Sloane | 2024-10-25T07:44:48 | oeisdata/seq/A001/A001526.seq | 0218aaefc306c0a870b7bf4d84dbc503 |
A001527 | a(n) = 2 * Sum_{i=0..n} C(2^n-1, i). | [
"2",
"4",
"14",
"128",
"3882",
"412736",
"151223522",
"189581406208",
"820064805806914",
"12419746847290729472",
"668590083306794321516802",
"129667782549203712117025325056",
"91624448643446654575608517356620802",
"238057970008583161105667221977375792447488"
] | [
"nonn",
"easy"
] | 17 | 0 | 1 | [
"A001527",
"A046855"
] | [
"M1286",
"N0493"
] | N. J. A. Sloane | 2020-04-26T22:53:38 | oeisdata/seq/A001/A001527.seq | c0e2fcf2c658217448f8d5b62d239196 |
A001528 | NPN-equivalence classes of switching functions of exactly n variables. | [
"1",
"1",
"2",
"10",
"208",
"615904",
"200253951911058"
] | [
"nonn",
"more"
] | 32 | 0 | 3 | null | [
"M1991",
"N0785"
] | N. J. A. Sloane | 2022-02-01T23:44:36 | oeisdata/seq/A001/A001528.seq | 34d0bc30e62009cd486e581ab0ee7f82 |
A001529 | NPN-equivalence classes of threshold functions of n or fewer variables. | [
"1",
"2",
"3",
"6",
"15",
"63",
"567",
"14755",
"1366318"
] | [
"nonn",
"nice",
"more"
] | 24 | 0 | 2 | [
"A001529",
"A001530",
"A002078",
"A002079"
] | [
"M0809",
"N0306"
] | N. J. A. Sloane | 2025-07-08T16:26:32 | oeisdata/seq/A001/A001529.seq | 3954ba369924e06a0dabc1e0957a87a0 |
A001530 | NPN-equivalence classes of threshold functions of exactly n variables. | [
"1",
"1",
"1",
"3",
"9",
"48",
"504",
"14188",
"1351563"
] | [
"nonn",
"more"
] | 24 | 0 | 4 | [
"A001529",
"A001530"
] | [
"M2825",
"N1138"
] | N. J. A. Sloane | 2022-02-01T23:45:00 | oeisdata/seq/A001/A001530.seq | 0f3f5fa4ea71c359f2b46236aa0f07fd |
A001531 | Number of self-dual Boolean functions of n variables that are distinct under complementation/permutation. | [
"1",
"1",
"3",
"7",
"83",
"109950",
"28613442061634",
"32966964611113760521683249750048",
"623226477875973310927522916529663444655632673539934117923988862064800"
] | [
"nonn",
"nice"
] | 34 | 0 | 3 | [
"A000610",
"A000616",
"A001531"
] | [
"M2706",
"N1085"
] | N. J. A. Sloane | 2025-07-08T16:26:39 | oeisdata/seq/A001/A001531.seq | be943e8b2ceb7fa193fee72f6dcb8919 |
A001532 | Number of NP-equivalence classes of self-dual threshold functions of n or fewer variables; number of majority (i.e., decisive and weighted) games with n players. | [
"1",
"1",
"2",
"3",
"7",
"21",
"135",
"2470",
"175428",
"52980624"
] | [
"nonn",
"nice",
"more"
] | 91 | 1 | 3 | [
"A000617",
"A001532",
"A002077",
"A002078",
"A002079",
"A002080",
"A003184",
"A109456",
"A132183",
"A189359"
] | [
"M0852",
"N0324"
] | N. J. A. Sloane | 2025-12-15T10:04:01 | oeisdata/seq/A001/A001532.seq | 2c21564c00b3af5301ad636f39cde67a |
A001533 | a(n) = (8*n+1)*(8*n+7). | [
"7",
"135",
"391",
"775",
"1287",
"1927",
"2695",
"3591",
"4615",
"5767",
"7047",
"8455",
"9991",
"11655",
"13447",
"15367",
"17415",
"19591",
"21895",
"24327",
"26887",
"29575",
"32391",
"35335",
"38407",
"41607",
"44935",
"48391",
"51975",
"55687",
"5952... | [
"nonn",
"easy"
] | 55 | 0 | 1 | [
"A001533",
"A001539",
"A004771",
"A017077",
"A017113",
"A028560",
"A250129"
] | null | N. J. A. Sloane | 2024-10-25T07:40:35 | oeisdata/seq/A001/A001533.seq | 9eb4a3c1b783b93374c5b41989b924bb |
A001534 | a(n) = (9*n+1)*(9*n+8). | [
"8",
"170",
"494",
"980",
"1628",
"2438",
"3410",
"4544",
"5840",
"7298",
"8918",
"10700",
"12644",
"14750",
"17018",
"19448",
"22040",
"24794",
"27710",
"30788",
"34028",
"37430",
"40994",
"44720",
"48608",
"52658",
"56870",
"61244",
"65780",
"70478",
"75... | [
"nonn",
"easy"
] | 43 | 0 | 1 | [
"A001534",
"A017173",
"A017257"
] | null | N. J. A. Sloane | 2024-10-18T19:39:38 | oeisdata/seq/A001/A001534.seq | f3f9c55320351f98e5241f24f654f402 |
A001535 | a(n) = (10n+1)*(10n+9). | [
"9",
"209",
"609",
"1209",
"2009",
"3009",
"4209",
"5609",
"7209",
"9009",
"11009",
"13209",
"15609",
"18209",
"21009",
"24009",
"27209",
"30609",
"34209",
"38009",
"42009",
"46209",
"50609",
"55209",
"60009",
"65009",
"70209",
"75609",
"81209",
"87009",
"... | [
"nonn",
"easy"
] | 28 | 0 | 1 | [
"A001535",
"A001622",
"A017281",
"A017377"
] | null | N. J. A. Sloane | 2023-02-20T03:14:37 | oeisdata/seq/A001/A001535.seq | 4d14047cdceeb80f915e1a21dea607f0 |
A001536 | a(n) = (11*n+1)*(11*n+10). | [
"10",
"252",
"736",
"1462",
"2430",
"3640",
"5092",
"6786",
"8722",
"10900",
"13320",
"15982",
"18886",
"22032",
"25420",
"29050",
"32922",
"37036",
"41392",
"45990",
"50830",
"55912",
"61236",
"66802",
"72610",
"78660",
"84952",
"91486",
"98262",
"105280",
... | [
"nonn",
"easy"
] | 33 | 0 | 1 | [
"A001536",
"A017401",
"A017509"
] | null | N. J. A. Sloane | 2025-08-15T05:48:31 | oeisdata/seq/A001/A001536.seq | dfa923e961cd315ea773ea312e3c82da |
A001537 | Invertible Boolean functions with AG(n,2) acting on the domain and range. | [
"1",
"1",
"4",
"302",
"2569966041123963092",
"76230976900860740792605252293646252383143627390965685153124757864"
] | [
"nonn"
] | 29 | 1 | 3 | null | [
"M3723",
"N1522"
] | N. J. A. Sloane | 2022-02-02T04:51:56 | oeisdata/seq/A001/A001537.seq | 86ce5c7f2865a53ad35f00e049d3b808 |
A001538 | a(n) = (12*n+1)*(12*n+11). | [
"11",
"299",
"875",
"1739",
"2891",
"4331",
"6059",
"8075",
"10379",
"12971",
"15851",
"19019",
"22475",
"26219",
"30251",
"34571",
"39179",
"44075",
"49259",
"54731",
"60491",
"66539",
"72875",
"79499",
"86411",
"93611",
"101099",
"108875",
"116939",
"12529... | [
"nonn",
"easy"
] | 37 | 0 | 1 | [
"A001533",
"A001538",
"A017533",
"A017653"
] | null | N. J. A. Sloane | 2024-10-25T17:05:36 | oeisdata/seq/A001/A001538.seq | 8870a994d62af31f7a4b31b77f8eda2e |
A001539 | a(n) = (4*n+1)*(4*n+3). | [
"3",
"35",
"99",
"195",
"323",
"483",
"675",
"899",
"1155",
"1443",
"1763",
"2115",
"2499",
"2915",
"3363",
"3843",
"4355",
"4899",
"5475",
"6083",
"6723",
"7395",
"8099",
"8835",
"9603",
"10403",
"11235",
"12099",
"12995",
"13923",
"14883",
"15875",
"... | [
"nonn",
"easy"
] | 69 | 0 | 1 | [
"A000217",
"A000290",
"A000466",
"A001533",
"A001538",
"A001539",
"A004767",
"A016286",
"A016813",
"A016826",
"A133766",
"A154633",
"A157142"
] | null | N. J. A. Sloane | 2024-10-23T17:21:15 | oeisdata/seq/A001/A001539.seq | fb10528bec92358d779a1e4dddef9135 |
A001540 | Number of transpositions needed to generate permutations of length n. | [
"0",
"2",
"8",
"36",
"184",
"1110",
"7776",
"62216",
"559952",
"5599530",
"61594840",
"739138092",
"9608795208",
"134523132926",
"2017846993904",
"32285551902480",
"548854382342176",
"9879378882159186",
"187708198761024552",
"3754163975220491060",
"78837443479630312280",
"1... | [
"nonn",
"easy",
"nice"
] | 54 | 1 | 2 | [
"A001540",
"A009179"
] | [
"M1856",
"N0734"
] | N. J. A. Sloane | 2025-09-24T17:18:18 | oeisdata/seq/A001/A001540.seq | aecd78d43a7d3d4fa028e3a1cce3a5c6 |
A001541 | a(0) = 1, a(1) = 3; for n > 1, a(n) = 6*a(n-1) - a(n-2). | [
"1",
"3",
"17",
"99",
"577",
"3363",
"19601",
"114243",
"665857",
"3880899",
"22619537",
"131836323",
"768398401",
"4478554083",
"26102926097",
"152139002499",
"886731088897",
"5168247530883",
"30122754096401",
"175568277047523",
"1023286908188737",
"5964153172084899",
"3... | [
"nonn",
"easy",
"nice"
] | 480 | 0 | 2 | [
"A001109",
"A001333",
"A001541",
"A001542",
"A001601",
"A003499",
"A005319",
"A046090",
"A053142",
"A055792",
"A055997",
"A056771",
"A077420",
"A082532",
"A084130",
"A132592",
"A188645"
] | [
"M3037",
"N1231"
] | N. J. A. Sloane | 2025-12-20T13:19:45 | oeisdata/seq/A001/A001541.seq | c71771573136c97de80b53551fccdba3 |
A001542 | a(n) = 6*a(n-1) - a(n-2) for n > 1, a(0)=0 and a(1)=2. | [
"0",
"2",
"12",
"70",
"408",
"2378",
"13860",
"80782",
"470832",
"2744210",
"15994428",
"93222358",
"543339720",
"3166815962",
"18457556052",
"107578520350",
"627013566048",
"3654502875938",
"21300003689580",
"124145519261542",
"723573111879672"
] | [
"nonn",
"easy",
"nice"
] | 307 | 0 | 2 | [
"A000129",
"A001108",
"A001353",
"A001541",
"A001542",
"A001653",
"A001835",
"A003499",
"A007805",
"A007913",
"A115598",
"A125650",
"A125651",
"A125652",
"A391706"
] | [
"M2030",
"N0802"
] | N. J. A. Sloane | 2025-12-20T06:31:22 | oeisdata/seq/A001/A001542.seq | 0a5446470f6e6d48733d5ce567a10a1b |
A001543 | a(0) = 1, a(n) = 5 + Product_{i=0..n-1} a(i) for n > 0. | [
"1",
"6",
"11",
"71",
"4691",
"21982031",
"483209576974811",
"233491495280173380882643611671",
"54518278368171228201482876236565907627201914279213829353891"
] | [
"nonn"
] | 62 | 0 | 2 | [
"A001543",
"A177888"
] | [
"M4091",
"N1699"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001543.seq | fe31eba803b8da5bdf58f99fe855c2c8 |
A001544 | A nonlinear recurrence: a(n) = a(n-1)^2 - 6*a(n-1) + 6, with a(0) = 1, a(1) = 7. | [
"1",
"7",
"13",
"97",
"8833",
"77968897",
"6079148431583233",
"36956045653220845240164417232897",
"1365749310322943329964576677590044473746108255675592519835615233"
] | [
"nonn"
] | 41 | 0 | 2 | [
"A001544",
"A177888"
] | [
"M4346",
"N1820"
] | N. J. A. Sloane | 2025-11-05T15:35:23 | oeisdata/seq/A001/A001544.seq | d700cf587f5ad7d2c80e59aef7539bc0 |
A001545 | a(n) = (5*n+1)*(5*n+4). | [
"4",
"54",
"154",
"304",
"504",
"754",
"1054",
"1404",
"1804",
"2254",
"2754",
"3304",
"3904",
"4554",
"5254",
"6004",
"6804",
"7654",
"8554",
"9504",
"10504",
"11554",
"12654",
"13804",
"15004",
"16254",
"17554",
"18904",
"20304",
"21754",
"23254",
"248... | [
"nonn",
"easy"
] | 48 | 0 | 1 | [
"A000217",
"A001545",
"A001622",
"A016861",
"A016897",
"A177059",
"A200135",
"A200138"
] | null | N. J. A. Sloane | 2024-10-24T15:42:26 | oeisdata/seq/A001/A001545.seq | 9eb8ecc2d975f7421a2b0a462b8f73e5 |
A001546 | a(n) = (8*n+1)*(8*n+3)*(8*n+5)*(8*n+7). | [
"105",
"19305",
"156009",
"606825",
"1666665",
"3728745",
"7284585",
"12924009",
"21335145",
"33304425",
"49716585",
"71554665",
"99900009",
"135932265",
"180929385",
"236267625",
"303421545",
"383964009",
"479566185",
"591997545",
"723125865",
"874917225",
"1049436009",
... | [
"nonn",
"easy"
] | 37 | 0 | 1 | null | null | N. J. A. Sloane | 2022-09-08T08:44:29 | oeisdata/seq/A001/A001546.seq | e7164bc8a05f36bb2df6feeb8553bfbc |
A001547 | a(n) = (7*n+1)*(7*n+2)*(7*n+4). | [
"8",
"792",
"4320",
"12650",
"27840",
"51948",
"87032",
"135150",
"198360",
"278720",
"378288",
"499122",
"643280",
"812820",
"1009800",
"1236278",
"1494312",
"1785960",
"2113280",
"2478330",
"2883168",
"3329852",
"3820440",
"4356990",
"4941560",
"5576208",
"62629... | [
"nonn",
"easy"
] | 24 | 0 | 1 | null | null | N. J. A. Sloane | 2025-09-22T16:00:15 | oeisdata/seq/A001/A001547.seq | 16be34c4c0f902b43acd2dacffa31c38 |
A001548 | Number of connected linear spaces with n (unlabeled) points. | [
"1",
"1",
"0",
"1",
"1",
"2",
"4",
"13",
"42",
"308",
"4845",
"227613",
"28639650"
] | [
"nonn",
"hard",
"nice",
"more"
] | 41 | 0 | 6 | [
"A001200",
"A001548",
"A056642"
] | [
"M1270",
"N0489"
] | N. J. A. Sloane | 2024-09-22T07:23:56 | oeisdata/seq/A001/A001548.seq | d5406ccb70ed6494a3568eccb2da25a2 |
A001549 | Related to Gilbreath conjecture. | [
"4",
"10",
"17",
"18",
"30",
"34",
"69",
"109",
"111",
"189",
"192",
"193",
"194",
"195",
"311",
"763",
"898",
"900",
"2215",
"2810",
"2811",
"2812",
"2813",
"3417",
"4260",
"6000",
"6002",
"6003",
"6004",
"23331",
"31569",
"31601",
"31602",
"31605",... | [
"nonn"
] | 23 | 1 | 1 | [
"A000232",
"A001549",
"A036277"
] | [
"M3376",
"N1360"
] | N. J. A. Sloane | 2023-05-10T10:02:02 | oeisdata/seq/A001/A001549.seq | cc87b5c5696b935c8ece7605fe29e2c2 |
A001550 | a(n) = 1^n + 2^n + 3^n. | [
"3",
"6",
"14",
"36",
"98",
"276",
"794",
"2316",
"6818",
"20196",
"60074",
"179196",
"535538",
"1602516",
"4799354",
"14381676",
"43112258",
"129271236",
"387682634",
"1162785756",
"3487832978",
"10462450356",
"31385253914",
"94151567436",
"282446313698",
"84732216... | [
"nonn",
"easy",
"nice"
] | 95 | 0 | 1 | [
"A000051",
"A000079",
"A000244",
"A001550",
"A001576",
"A001579",
"A007689",
"A034472",
"A034513",
"A074501",
"A074580",
"A103438"
] | [
"M2580",
"N1020"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001550.seq | c46a111c41a6445e900c112e8d464b37 |
A001551 | a(n) = 1^n + 2^n + 3^n + 4^n. | [
"4",
"10",
"30",
"100",
"354",
"1300",
"4890",
"18700",
"72354",
"282340",
"1108650",
"4373500",
"17312754",
"68711380",
"273234810",
"1088123500",
"4338079554",
"17309140420",
"69107159370",
"276040692700",
"1102999460754",
"4408508961460",
"17623571298330",
"704628957... | [
"nonn",
"easy"
] | 66 | 0 | 1 | [
"A001551",
"A103438"
] | [
"M3397",
"N1375"
] | N. J. A. Sloane | 2025-09-22T16:00:15 | oeisdata/seq/A001/A001551.seq | 9ddb63d2f99860bd1d8c37984a584945 |
A001552 | a(n) = 1^n + 2^n + ... + 5^n. | [
"5",
"15",
"55",
"225",
"979",
"4425",
"20515",
"96825",
"462979",
"2235465",
"10874275",
"53201625",
"261453379",
"1289414505",
"6376750435",
"31605701625",
"156925970179",
"780248593545",
"3883804424995",
"19349527020825",
"96470431101379",
"481245667164585",
"240180936... | [
"nonn",
"easy"
] | 57 | 0 | 1 | [
"A001552",
"A103438"
] | [
"M3863",
"N1584"
] | N. J. A. Sloane | 2025-09-22T16:00:15 | oeisdata/seq/A001/A001552.seq | 9cb5b4b1c403c777f47d6cde972f0674 |
A001553 | a(n) = 1^n + 2^n + ... + 6^n. | [
"6",
"21",
"91",
"441",
"2275",
"12201",
"67171",
"376761",
"2142595",
"12313161",
"71340451",
"415998681",
"2438235715",
"14350108521",
"84740914531",
"501790686201",
"2978035877635",
"17706908038281",
"105443761093411",
"628709267031321",
"3752628871164355",
"224181963075... | [
"nonn",
"easy"
] | 53 | 0 | 1 | [
"A001552",
"A001553",
"A103438"
] | [
"M4149",
"N1723"
] | N. J. A. Sloane | 2024-10-26T10:15:02 | oeisdata/seq/A001/A001553.seq | 2dc004f01b019158e34b9d79a16bf8af |
A001554 | a(n) = 1^n + 2^n + ... + 7^n. | [
"7",
"28",
"140",
"784",
"4676",
"29008",
"184820",
"1200304",
"7907396",
"52666768",
"353815700",
"2393325424",
"16279522916",
"111239118928",
"762963987380",
"5249352196144",
"36210966447236",
"250337422025488",
"1733857359003860",
"12027604452404464",
"83544895168776356",
... | [
"nonn",
"easy"
] | 46 | 0 | 1 | [
"A001554",
"A103438",
"A196837"
] | [
"M4393",
"N1850"
] | N. J. A. Sloane | 2024-10-26T10:16:03 | oeisdata/seq/A001/A001554.seq | e4fe7b58c816fba4a9adbbe9f2f4a038 |
A001555 | a(n) = 1^n + 2^n + ... + 8^n. | [
"8",
"36",
"204",
"1296",
"8772",
"61776",
"446964",
"3297456",
"24684612",
"186884496",
"1427557524",
"10983260016",
"84998999652",
"660994932816",
"5161010498484",
"40433724284976",
"317685943157892",
"2502137235710736",
"19748255868485844",
"156142792528260336",
"123646639... | [
"nonn",
"easy"
] | 51 | 0 | 1 | [
"A001018",
"A001552",
"A001554",
"A001555",
"A103438",
"A196837"
] | [
"M4520",
"N1914"
] | N. J. A. Sloane | 2024-10-26T10:17:36 | oeisdata/seq/A001/A001555.seq | a5305fed21c3a93e9e6492477c274d20 |
A001556 | a(n) = 1^n + 2^n + ... + 9^n. | [
"9",
"45",
"285",
"2025",
"15333",
"120825",
"978405",
"8080425",
"67731333",
"574304985",
"4914341925",
"42364319625",
"367428536133",
"3202860761145",
"28037802953445",
"246324856379625",
"2170706132009733",
"19179318935377305",
"169842891165484965",
"1506994510201252425"
] | [
"nonn"
] | 35 | 0 | 1 | [
"A001556",
"A103438",
"A196837"
] | [
"M4627",
"N1977"
] | N. J. A. Sloane | 2024-10-26T10:18:46 | oeisdata/seq/A001/A001556.seq | b4c21bde8383262591d5ba8ca31be723 |
A001557 | a(n) = 1^n + 2^n + ... + 10^n. | [
"10",
"55",
"385",
"3025",
"25333",
"220825",
"1978405",
"18080425",
"167731333",
"1574304985",
"14914341925",
"142364319625",
"1367428536133",
"13202860761145",
"128037802953445",
"1246324856379625",
"12170706132009733",
"119179318935377305",
"1169842891165484965",
"1150699451... | [
"nonn",
"easy"
] | 47 | 0 | 1 | [
"A001557",
"A103438",
"A196837"
] | [
"M4713",
"N2014"
] | N. J. A. Sloane | 2024-10-24T15:29:15 | oeisdata/seq/A001/A001557.seq | 8a0c25e1866209ca53bd1eb201466f56 |
A001558 | Number of hill-free Dyck paths of semilength n+3 and having length of first descent equal to 1 (a hill in a Dyck path is a peak at level 1). | [
"1",
"3",
"10",
"33",
"111",
"379",
"1312",
"4596",
"16266",
"58082",
"209010",
"757259",
"2760123",
"10114131",
"37239072",
"137698584",
"511140558",
"1904038986",
"7115422212",
"26668376994",
"100221202998",
"377570383518",
"1425706128480",
"5394898197448",
"2045467... | [
"nonn",
"easy"
] | 68 | 0 | 2 | [
"A000957",
"A001558",
"A111301",
"A118972",
"A118973"
] | [
"M2845",
"N1143"
] | N. J. A. Sloane | 2025-11-05T15:21:40 | oeisdata/seq/A001/A001558.seq | 1033f8980d6a9e7b95d15fa65b7364cd |
A001559 | a(0) = 1, a(1) = 4; thereafter a(n)*(2n + 10) - a(n-1)*(11n + 35) + a(n-2)*(8n + 2) + a(n-3)*(15n + 7) + a(n-4)*(4n - 2) = 0. | [
"1",
"4",
"15",
"54",
"193",
"690",
"2476",
"8928",
"32358",
"117866",
"431381",
"1585842",
"5853849",
"21690378",
"80650536",
"300845232",
"1125555054",
"4222603968",
"15881652606",
"59873283372",
"226214536506",
"856431978324",
"3248562071800",
"12344168149224",
"46... | [
"nonn"
] | 61 | 0 | 2 | null | [
"M3497",
"N1418"
] | N. J. A. Sloane | 2025-11-05T15:21:40 | oeisdata/seq/A001/A001559.seq | c421c2ea6514fd541b5c9511565db875 |
A001560 | Numbers with an even number of partitions. | [
"2",
"8",
"9",
"10",
"11",
"15",
"19",
"21",
"22",
"25",
"26",
"27",
"28",
"30",
"31",
"34",
"40",
"42",
"45",
"46",
"47",
"50",
"55",
"57",
"58",
"59",
"62",
"64",
"65",
"66",
"70",
"74",
"75",
"78",
"79",
"80",
"84",
"86",
"94",
"96",
... | [
"nonn",
"easy"
] | 40 | 1 | 1 | [
"A000041",
"A001560",
"A052001",
"A052002",
"A243935"
] | [
"M1823",
"N0724"
] | N. J. A. Sloane | 2025-11-05T15:35:23 | oeisdata/seq/A001/A001560.seq | 4dd52a9fde30b123a9504f7a0943344d |
A001561 | a(n) = (7*n+3)*(7*n+5)*(7*n+6). | [
"90",
"1560",
"6460",
"16848",
"34782",
"62320",
"101520",
"154440",
"223138",
"309672",
"416100",
"544480",
"696870",
"875328",
"1081912",
"1318680",
"1587690",
"1891000",
"2230668",
"2608752",
"3027310",
"3488400",
"3994080",
"4546408",
"5147442",
"5799240",
"65... | [
"nonn",
"easy"
] | 19 | 0 | 1 | null | null | N. J. A. Sloane | 2025-09-22T16:00:15 | oeisdata/seq/A001/A001561.seq | 443ef512e9eb48a0b3dfbb364833883e |
A001562 | Numbers n such that (10^n + 1)/11 is a prime. | [
"5",
"7",
"19",
"31",
"53",
"67",
"293",
"641",
"2137",
"3011",
"268207",
"1600787"
] | [
"nonn",
"hard",
"more"
] | 58 | 1 | 1 | [
"A001562",
"A054416",
"A309358"
] | [
"M3767",
"N1537"
] | N. J. A. Sloane | 2025-02-16T08:32:24 | oeisdata/seq/A001/A001562.seq | b3732f1b8924524f39432219149ee208 |
A001563 | a(n) = n*n! = (n+1)! - n!. | [
"0",
"1",
"4",
"18",
"96",
"600",
"4320",
"35280",
"322560",
"3265920",
"36288000",
"439084800",
"5748019200",
"80951270400",
"1220496076800",
"19615115520000",
"334764638208000",
"6046686277632000",
"115242726703104000",
"2311256907767808000",
"48658040163532800000",
"1072... | [
"nonn",
"easy",
"nice"
] | 231 | 0 | 3 | [
"A000142",
"A001563",
"A002024",
"A002775",
"A047920",
"A047922",
"A053495",
"A055089",
"A091363",
"A091364",
"A094485",
"A123513",
"A143946",
"A163931",
"A185105",
"A229837",
"A239069",
"A282466",
"A322383",
"A322384"
] | [
"M3545",
"N1436"
] | N. J. A. Sloane | 2025-11-05T15:21:40 | oeisdata/seq/A001/A001563.seq | 814c96c6e081aeeff1db81f20d1883ad |
A001564 | 2nd differences of factorial numbers. | [
"1",
"3",
"14",
"78",
"504",
"3720",
"30960",
"287280",
"2943360",
"33022080",
"402796800",
"5308934400",
"75203251200",
"1139544806400",
"18394619443200",
"315149522688000",
"5711921639424000",
"109196040425472000",
"2196014181064704000",
"46346783255764992000",
"10242517454... | [
"nonn",
"easy"
] | 78 | 0 | 2 | [
"A000142",
"A001563",
"A001564",
"A002061",
"A010027",
"A047920",
"A306209"
] | [
"M2972",
"N1202"
] | N. J. A. Sloane | 2025-08-24T02:05:56 | oeisdata/seq/A001/A001564.seq | 6e77f74445b78c580d424759d2037fb9 |
A001565 | 3rd differences of factorial numbers. | [
"2",
"11",
"64",
"426",
"3216",
"27240",
"256320",
"2656080",
"30078720",
"369774720",
"4906137600",
"69894316800",
"1064341555200",
"17255074636800",
"296754903244800",
"5396772116736000",
"103484118786048000",
"2086818140639232000",
"44150769074700288000",
"977904962186600448... | [
"nonn",
"easy"
] | 48 | 0 | 1 | [
"A001565",
"A047920",
"A180196"
] | [
"M2004",
"N0793"
] | N. J. A. Sloane | 2025-09-22T16:00:15 | oeisdata/seq/A001/A001565.seq | 0f6d66fdfe51a8a62a32a61410096c0a |
A001566 | a(0) = 3; thereafter, a(n) = a(n-1)^2 - 2. | [
"3",
"7",
"47",
"2207",
"4870847",
"23725150497407",
"562882766124611619513723647",
"316837008400094222150776738483768236006420971486980607"
] | [
"easy",
"nonn",
"nice"
] | 223 | 0 | 1 | [
"A000032",
"A000045",
"A001566",
"A002812",
"A003010",
"A003423",
"A003487",
"A050614",
"A058635",
"A079585",
"A088334",
"A094874",
"A145274",
"A145502",
"A181393",
"A181419",
"A186750",
"A186751",
"A338304"
] | [
"M2705",
"N1084"
] | N. J. A. Sloane | 2026-01-03T05:47:32 | oeisdata/seq/A001/A001566.seq | c6a0f437e980c1c1ba054cb8cc12d01d |
A001567 | Fermat pseudoprimes to base 2, also called Sarrus numbers or Poulet numbers. | [
"341",
"561",
"645",
"1105",
"1387",
"1729",
"1905",
"2047",
"2465",
"2701",
"2821",
"3277",
"4033",
"4369",
"4371",
"4681",
"5461",
"6601",
"7957",
"8321",
"8481",
"8911",
"10261",
"10585",
"11305",
"12801",
"13741",
"13747",
"13981",
"14491",
"15709",
... | [
"nonn",
"nice",
"changed"
] | 263 | 1 | 1 | [
"A001220",
"A001567",
"A002997",
"A005382",
"A005935",
"A005936",
"A005937",
"A005938",
"A005939",
"A020136",
"A020137",
"A020228",
"A052155",
"A083737",
"A084653",
"A153508"
] | [
"M5441",
"N2365"
] | N. J. A. Sloane | 2026-01-14T08:21:48 | oeisdata/seq/A001/A001567.seq | 4004e4294d0ffcd8804d03ada24fd128 |
A001568 | Related to 3-line Latin rectangles. | [
"1",
"-1",
"-1",
"2",
"49",
"629",
"6961",
"38366",
"-1899687",
"-133065253",
"-6482111309",
"-281940658286",
"-10702380933551",
"-247708227641863",
"14512103549430397",
"3377044611825908414",
"433180638973276282801",
"47474992085447610990231"
] | [
"sign",
"more"
] | 33 | 1 | 4 | null | [
"M2171",
"N0867"
] | N. J. A. Sloane | 2025-09-22T16:00:15 | oeisdata/seq/A001/A001568.seq | e7d3ad4dbdda57d9e8ab56baa8153fdd |
A001569 | Sum_{n>=0} a(n)*x^n/n!^2 = BesselI(0,2*(1-exp(x))^(1/2)). | [
"1",
"-1",
"-1",
"2",
"37",
"329",
"1501",
"-31354",
"-1451967",
"-39284461",
"-737652869",
"560823394",
"1103386777549",
"82520245792997",
"4398448305245905",
"168910341581721494",
"998428794798272641",
"-720450682719825322809",
"-105099789680808769094057",
"-10594247095804692... | [
"sign",
"easy"
] | 35 | 0 | 4 | null | [
"M2161",
"N0861"
] | N. J. A. Sloane | 2021-12-26T21:04:49 | oeisdata/seq/A001/A001569.seq | 5e8610db6437c001b6d05707712dd0e1 |
A001570 | Numbers k such that k^2 is centered hexagonal. | [
"1",
"13",
"181",
"2521",
"35113",
"489061",
"6811741",
"94875313",
"1321442641",
"18405321661",
"256353060613",
"3570537526921",
"49731172316281",
"692665874901013",
"9647591076297901",
"134373609193269601",
"1871582937629476513",
"26067787517619401581",
"363077442309042145621",... | [
"nonn",
"easy",
"nice"
] | 160 | 1 | 2 | [
"A001075",
"A001570",
"A001921",
"A001922",
"A003500",
"A006051",
"A007655",
"A028231",
"A076139",
"A076140",
"A077416",
"A077417",
"A094954",
"A102871",
"A122571",
"A188646",
"A238379",
"A302329"
] | [
"M4915",
"N2108"
] | N. J. A. Sloane | 2025-11-05T15:35:23 | oeisdata/seq/A001/A001570.seq | 5741b0897faeda5e61b07efcc2b87688 |
A001571 | a(n) = 4*a(n-1) - a(n-2) + 1, with a(0) = 0, a(1) = 2. | [
"0",
"2",
"9",
"35",
"132",
"494",
"1845",
"6887",
"25704",
"95930",
"358017",
"1336139",
"4986540",
"18610022",
"69453549",
"259204175",
"967363152",
"3610248434",
"13473630585",
"50284273907",
"187663465044",
"700369586270",
"2613814880037",
"9754889933879",
"364057... | [
"nonn",
"easy"
] | 106 | 0 | 2 | [
"A001353",
"A001571",
"A001834",
"A061278",
"A071954",
"A082840"
] | [
"M1928",
"N0762"
] | N. J. A. Sloane | 2025-11-05T15:35:23 | oeisdata/seq/A001/A001571.seq | 670688bb3a090c255c14c31e6f9cd0a6 |
A001572 | Related to series-parallel networks. | [
"1",
"1",
"1",
"1",
"3",
"5",
"17",
"41",
"127",
"365",
"1119",
"3413",
"10685",
"33561",
"106827",
"342129",
"1104347",
"3584649",
"11701369",
"38374065",
"126395259",
"417908329",
"1386618307",
"4615388353",
"15407188529",
"51569669429",
"173033992311",
"58190... | [
"nonn",
"easy"
] | 28 | 0 | 5 | [
"A000084",
"A001572",
"A144962"
] | [
"M2500",
"N0989"
] | N. J. A. Sloane | 2021-06-04T22:42:46 | oeisdata/seq/A001/A001572.seq | ccea3a7a19eeefdf71491ddd032b7843 |
A001573 | Another approximation to A000084(n). | [
"1",
"2",
"4",
"9",
"23",
"63",
"177",
"514",
"1527",
"4625",
"14230",
"44357",
"139779",
"444558",
"1425151",
"4600339",
"14939849",
"48778197",
"160019885",
"527200711"
] | [
"nonn",
"more"
] | 19 | 1 | 2 | [
"A000084",
"A001573",
"A058585"
] | [
"M1190",
"N0460"
] | N. J. A. Sloane | 2015-06-27T15:07:53 | oeisdata/seq/A001/A001573.seq | dcc416e647c4ab9ddf516b871b96ccfe |
A001574 | Colored series-parallel networks. | [
"0",
"2",
"12",
"60",
"292",
"1438",
"7180",
"36566"
] | [
"nonn",
"more"
] | 20 | 1 | 2 | null | [
"M2029",
"N0801"
] | N. J. A. Sloane | 2023-01-14T02:09:09 | oeisdata/seq/A001/A001574.seq | 33a05e0cc7e208deb8e4c944376988c2 |
A001575 | Colored series-parallel networks. | [
"0",
"0",
"8",
"102",
"948",
"7900",
"62928",
"491832"
] | [
"nonn",
"more"
] | 16 | 1 | 3 | null | [
"M4567",
"N1944"
] | N. J. A. Sloane | 2023-01-14T02:09:20 | oeisdata/seq/A001/A001575.seq | 72fe236d1f3fb076f7ed030c6fe2a175 |
A001576 | a(n) = 1^n + 2^n + 4^n. | [
"3",
"7",
"21",
"73",
"273",
"1057",
"4161",
"16513",
"65793",
"262657",
"1049601",
"4196353",
"16781313",
"67117057",
"268451841",
"1073774593",
"4295032833",
"17180000257",
"68719738881",
"274878431233",
"1099512676353",
"4398048608257",
"17592190238721",
"70368752566... | [
"nonn",
"easy"
] | 68 | 0 | 1 | [
"A001550",
"A001576",
"A001579",
"A002061",
"A006095",
"A022166",
"A034513",
"A051154",
"A074501",
"A074580",
"A135576",
"A135577"
] | null | N. J. A. Sloane | 2025-09-22T16:00:15 | oeisdata/seq/A001/A001576.seq | c5391aa3102016295366de7417b126db |
A001577 | An operational recurrence. | [
"1",
"1",
"2",
"6",
"60",
"2880",
"2246400",
"135862272000",
"10376834265907200000",
"77540115374348238323712000000000",
"71611262431705169979126571320506685849600000000000000",
"799595359352229378487949660335170674324575940302246074414582988800000000000000000000000"
] | [
"nice",
"easy",
"nonn"
] | 21 | 1 | 3 | null | [
"M1718",
"N0681"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001577.seq | 11ad1d2613e7c88b32aef74b2949cc69 |
A001578 | Smallest primitive prime factor of Fibonacci number F(n), or 1 if F(n) has no primitive prime factor. | [
"1",
"1",
"2",
"3",
"5",
"1",
"13",
"7",
"17",
"11",
"89",
"1",
"233",
"29",
"61",
"47",
"1597",
"19",
"37",
"41",
"421",
"199",
"28657",
"23",
"3001",
"521",
"53",
"281",
"514229",
"31",
"557",
"2207",
"19801",
"3571",
"141961",
"107",
"73",
... | [
"nonn"
] | 69 | 1 | 3 | [
"A000045",
"A000057",
"A001578",
"A061488",
"A086597",
"A106535",
"A262341"
] | [
"M0603",
"N0217"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001578.seq | bb839ab6f120450fd0dd4476bda545f0 |
A001579 | a(n) = 3^n + 5^n + 6^n. | [
"3",
"14",
"70",
"368",
"2002",
"11144",
"63010",
"360248",
"2076802",
"12050504",
"70290850",
"411802328",
"2421454402",
"14282991464",
"84472462690",
"500716911608",
"2973740844802",
"17689728038024",
"105375041354530",
"628434388600088"
] | [
"easy",
"nonn"
] | 37 | 0 | 1 | [
"A001550",
"A001576",
"A001579",
"A034513",
"A074501",
"A074580"
] | null | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001579.seq | c059c92c89aea07fcd1f381e2d2a951e |
A001580 | a(n) = 2^n + n^2. | [
"1",
"3",
"8",
"17",
"32",
"57",
"100",
"177",
"320",
"593",
"1124",
"2169",
"4240",
"8361",
"16580",
"32993",
"65792",
"131361",
"262468",
"524649",
"1048976",
"2097593",
"4194788",
"8389137",
"16777792",
"33555057",
"67109540",
"134218457",
"268436240",
"5... | [
"nonn",
"easy"
] | 37 | 0 | 2 | [
"A000079",
"A000217",
"A001580"
] | null | N. J. A. Sloane | 2025-12-25T22:45:55 | oeisdata/seq/A001/A001580.seq | 5c4e91ca18ad3f8c74bb90a6e5e80e99 |
A001581 | Winning moves in Fibonacci nim. | [
"4",
"10",
"14",
"20",
"24",
"30",
"36",
"40",
"46",
"50",
"56",
"60",
"66",
"72",
"76",
"82",
"86",
"92",
"96",
"102",
"108",
"112",
"118",
"122",
"128",
"132",
"138",
"150",
"160",
"169",
"176",
"186",
"192",
"196",
"202",
"206",
"212",
"21... | [
"nonn",
"nice"
] | 58 | 1 | 1 | [
"A001581",
"A030193"
] | [
"M3374",
"N1359"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001581.seq | f2327c0fec41b20b647759ab5a0ac762 |
A001582 | Product of Fibonacci and Pell numbers. | [
"1",
"2",
"10",
"36",
"145",
"560",
"2197",
"8568",
"33490",
"130790",
"510949",
"1995840",
"7796413",
"30454814",
"118965250",
"464711184",
"1815292333",
"7091038640",
"27699580729",
"108202305420",
"422668460890",
"1651061182538",
"6449506621417",
"25193576136960"
] | [
"nonn",
"easy",
"nice"
] | 103 | 0 | 2 | [
"A000045",
"A000129",
"A001582"
] | [
"M1966",
"N0779"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001582.seq | 7ced89bc7a3cd8b0edad8579301bf147 |
A001583 | Artiads: the primes p == 1 (mod 5) for which Fibonacci((p-1)/5) is divisible by p. | [
"211",
"281",
"421",
"461",
"521",
"691",
"881",
"991",
"1031",
"1151",
"1511",
"1601",
"1871",
"1951",
"2221",
"2591",
"3001",
"3251",
"3571",
"3851",
"4021",
"4391",
"4441",
"4481",
"4621",
"4651",
"4691",
"4751",
"4871",
"5081",
"5281",
"5381",
"553... | [
"nonn",
"nice"
] | 113 | 1 | 1 | [
"A000045",
"A001583",
"A024894",
"A030430",
"A047650",
"A270798",
"A270800"
] | [
"M5413",
"N2351"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001583.seq | 11755e65e9909403fbd741ea8277608c |
A001584 | A generalized Fibonacci sequence. | [
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"2",
"2",
"2",
"4",
"4",
"4",
"7",
"7",
"8",
"12",
"12",
"16",
"21",
"21",
"31",
"37",
"38",
"58",
"65",
"71",
"106",
"114",
"135",
"191",
"201",
"257",
"341",
"359",
"485",
"605",
"652",
"904",
"... | [
"nonn",
"easy"
] | 48 | 0 | 9 | [
"A001584",
"A017817"
] | [
"M0235",
"N0080"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001584.seq | 4a40f52228e3f18a2bdade7216c5b974 |
A001585 | a(n) = 3^n + n^3. | [
"1",
"4",
"17",
"54",
"145",
"368",
"945",
"2530",
"7073",
"20412",
"60049",
"178478",
"533169",
"1596520",
"4785713",
"14352282",
"43050817",
"129145076",
"387426321",
"1162268326",
"3486792401",
"10460362464",
"31381070257",
"94143190994",
"282429550305",
"8472886... | [
"nonn",
"easy"
] | 27 | 0 | 2 | [
"A001580",
"A001585"
] | null | N. J. A. Sloane | 2025-12-25T22:45:43 | oeisdata/seq/A001/A001585.seq | b161c0a36e6f0ecba1f6cbddb11870bd |
A001586 | Generalized Euler numbers, or Springer numbers. | [
"1",
"1",
"3",
"11",
"57",
"361",
"2763",
"24611",
"250737",
"2873041",
"36581523",
"512343611",
"7828053417",
"129570724921",
"2309644635483",
"44110959165011",
"898621108880097",
"19450718635716001",
"445777636063460643",
"10784052561125704811",
"274613643571568682777",
"... | [
"nonn",
"easy",
"nice"
] | 252 | 0 | 3 | [
"A000281",
"A000464",
"A001586",
"A007836",
"A046802",
"A079858",
"A081658",
"A098432",
"A153641",
"A185417",
"A185418",
"A212435",
"A349264",
"A349271"
] | [
"M2908",
"N1169"
] | N. J. A. Sloane | 2025-11-05T15:21:40 | oeisdata/seq/A001/A001586.seq | 50e244e76bd507bed5855143de733a8a |
A001587 | Generalized Euler numbers. | [
"2",
"6",
"46",
"522",
"7970",
"152166",
"3487246",
"93241002",
"2849229890",
"97949265606",
"3741386059246",
"157201459863882",
"7205584123783010",
"357802951084619046",
"19133892392367261646",
"1096291279711115037162",
"67000387673723462963330",
"4350684698032741048452486",
"29... | [
"nonn"
] | 61 | 0 | 1 | [
"A000111",
"A000192",
"A000411",
"A001587",
"A225147",
"A349264"
] | [
"M1715",
"N0679"
] | N. J. A. Sloane | 2025-09-22T16:00:15 | oeisdata/seq/A001/A001587.seq | 5ae4cc3c817e9890eee70e8482b1879b |
A001588 | a(n) = a(n-1) + a(n-2) - 1. | [
"1",
"3",
"3",
"5",
"7",
"11",
"17",
"27",
"43",
"69",
"111",
"179",
"289",
"467",
"755",
"1221",
"1975",
"3195",
"5169",
"8363",
"13531",
"21893",
"35423",
"57315",
"92737",
"150051",
"242787",
"392837",
"635623",
"1028459",
"1664081",
"2692539",
"435... | [
"nonn",
"easy"
] | 93 | 0 | 2 | [
"A000045",
"A001588",
"A001611",
"A001906"
] | [
"M2279",
"N0901"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001588.seq | 169b38e9c6b5e35126b9e7e15e5d9629 |
A001589 | a(n) = 4^n + n^4. | [
"1",
"5",
"32",
"145",
"512",
"1649",
"5392",
"18785",
"69632",
"268705",
"1058576",
"4208945",
"16797952",
"67137425",
"268473872",
"1073792449",
"4295032832",
"17179952705",
"68719581712",
"274878037265",
"1099511787776",
"4398046705585",
"17592186278672",
"7036874445... | [
"nonn",
"easy"
] | 62 | 0 | 2 | [
"A001580",
"A001585",
"A001589"
] | null | N. J. A. Sloane | 2025-12-26T05:35:30 | oeisdata/seq/A001/A001589.seq | ad1d5d01f8391047f22eb8cd4d018063 |
A001590 | Tribonacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) with a(0)=0, a(1)=1, a(2)=0. | [
"0",
"1",
"0",
"1",
"2",
"3",
"6",
"11",
"20",
"37",
"68",
"125",
"230",
"423",
"778",
"1431",
"2632",
"4841",
"8904",
"16377",
"30122",
"55403",
"101902",
"187427",
"344732",
"634061",
"1166220",
"2145013",
"3945294",
"7256527",
"13346834",
"24548655",
... | [
"nonn",
"easy"
] | 229 | 0 | 5 | [
"A000045",
"A000073",
"A001590",
"A027053",
"A027907",
"A078042",
"A145579",
"A278038"
] | [
"M0784",
"N0296"
] | N. J. A. Sloane | 2025-12-14T15:16:43 | oeisdata/seq/A001/A001590.seq | ba155f877695360bf170b92780d6d278 |
A001591 | Pentanacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4) + a(n-5), a(0)=a(1)=a(2)=a(3)=0, a(4)=1. | [
"0",
"0",
"0",
"0",
"1",
"1",
"2",
"4",
"8",
"16",
"31",
"61",
"120",
"236",
"464",
"912",
"1793",
"3525",
"6930",
"13624",
"26784",
"52656",
"103519",
"203513",
"400096",
"786568",
"1546352",
"3040048",
"5976577",
"11749641",
"23099186",
"45411804",
"... | [
"nonn",
"easy"
] | 259 | 0 | 7 | [
"A001591",
"A035343",
"A048887",
"A074048",
"A074062",
"A092921",
"A106303",
"A123126",
"A123127"
] | [
"M1122",
"N0429"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001591.seq | e3f2d379cf9a7e5c56aed17889c67e49 |
A001592 | Hexanacci numbers: a(n+1) = a(n)+...+a(n-5) with a(0)=...=a(4)=0, a(5)=1. | [
"0",
"0",
"0",
"0",
"0",
"1",
"1",
"2",
"4",
"8",
"16",
"32",
"63",
"125",
"248",
"492",
"976",
"1936",
"3840",
"7617",
"15109",
"29970",
"59448",
"117920",
"233904",
"463968",
"920319",
"1825529",
"3621088",
"7182728",
"14247536",
"28261168",
"5605836... | [
"nonn",
"easy"
] | 154 | 0 | 8 | [
"A001592",
"A048887",
"A092921"
] | [
"M1128",
"N0431"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001592.seq | b1691ef3fb3fdc099f48448a90daae8b |
A001593 | a(n) = 5^n + n^5. | [
"1",
"6",
"57",
"368",
"1649",
"6250",
"23401",
"94932",
"423393",
"2012174",
"9865625",
"48989176",
"244389457",
"1221074418",
"6104053449",
"30518337500",
"152588939201",
"762940872982",
"3814699155193",
"19073488804224",
"95367434840625",
"476837162287226",
"2384185796... | [
"nonn",
"easy"
] | 37 | 0 | 2 | [
"A001580",
"A001585",
"A001589",
"A001593"
] | null | N. J. A. Sloane | 2025-12-26T05:34:27 | oeisdata/seq/A001/A001593.seq | 26ab4927444436b5a3765d5307a10f77 |
A001594 | a(n) = 6^n + n^6. | [
"1",
"7",
"100",
"945",
"5392",
"23401",
"93312",
"397585",
"1941760",
"10609137",
"61466176",
"364568617",
"2179768320",
"13065520825",
"78371693632",
"470196375201",
"2821126684672",
"16926683582305",
"101559990680640",
"609359787056377",
"3656158504062976",
"219369507261... | [
"nonn",
"easy"
] | 36 | 0 | 2 | [
"A001580",
"A001585",
"A001589",
"A001593",
"A001594",
"A001596",
"A177068",
"A177069",
"A185277",
"A198401"
] | null | N. J. A. Sloane | 2025-12-26T20:56:52 | oeisdata/seq/A001/A001594.seq | ad385dce408eb77f3576d598633e28f3 |
A001595 | a(n) = a(n-1) + a(n-2) + 1, with a(0) = a(1) = 1. | [
"1",
"1",
"3",
"5",
"9",
"15",
"25",
"41",
"67",
"109",
"177",
"287",
"465",
"753",
"1219",
"1973",
"3193",
"5167",
"8361",
"13529",
"21891",
"35421",
"57313",
"92735",
"150049",
"242785",
"392835",
"635621",
"1028457",
"1664079",
"2692537",
"4356617",
... | [
"nonn",
"easy",
"nice"
] | 186 | 0 | 3 | [
"A000045",
"A000071",
"A001595",
"A006355",
"A033538",
"A049112",
"A049114",
"A101220",
"A109754",
"A128587"
] | [
"M2453",
"N0974"
] | N. J. A. Sloane | 2025-12-22T12:27:39 | oeisdata/seq/A001/A001595.seq | 81f93cab4e2db75637215239396db373 |
A001596 | a(n) = 7^n + n^7. | [
"1",
"8",
"177",
"2530",
"18785",
"94932",
"397585",
"1647086",
"7861953",
"45136576",
"292475249",
"1996813914",
"13877119009",
"96951758924",
"678328486353",
"4747732369318",
"33233199005057",
"232630924325880",
"1628414210130481"
] | [
"nonn",
"easy"
] | 27 | 0 | 2 | [
"A001580",
"A001585",
"A001589",
"A001593",
"A001594",
"A001596"
] | null | N. J. A. Sloane | 2022-09-08T08:44:29 | oeisdata/seq/A001/A001596.seq | 58e75dd8ec3d1fa27d3ff7c8eaea479f |
A001597 | Perfect powers: m^k where m > 0 and k >= 2. | [
"1",
"4",
"8",
"9",
"16",
"25",
"27",
"32",
"36",
"49",
"64",
"81",
"100",
"121",
"125",
"128",
"144",
"169",
"196",
"216",
"225",
"243",
"256",
"289",
"324",
"343",
"361",
"400",
"441",
"484",
"512",
"529",
"576",
"625",
"676",
"729",
"784",
... | [
"nonn",
"easy",
"nice"
] | 251 | 1 | 2 | [
"A000961",
"A001597",
"A007916",
"A023055",
"A023057",
"A025475",
"A025478",
"A053289",
"A070428",
"A072102",
"A072103",
"A072777",
"A074981",
"A075090",
"A075109",
"A076404",
"A089579",
"A089580",
"A097054",
"A239728",
"A239870",
"A246547",
"A246655"
] | [
"M3326",
"N1336"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001597.seq | dd573eb65f701c0959d51f70ed16592f |
A001598 | Number of terms in {b(1)..b(n)} relatively prime to b(n), where b(n) = A001597(n). | [
"1",
"1",
"1",
"3",
"2",
"5",
"5",
"4",
"2",
"9",
"5",
"8",
"5",
"13",
"12",
"8",
"5",
"17",
"8",
"6",
"11",
"14",
"11",
"23",
"7",
"23",
"26",
"11",
"16",
"14",
"15",
"31",
"10",
"28",
"16",
"24",
"15",
"37",
"9",
"39",
"16",
"20",
... | [
"nonn",
"easy"
] | 21 | 1 | 4 | null | [
"M2244",
"N0891"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001598.seq | bd0fde6b85d9612f495128d8f5ba4c6b |
A001599 | Harmonic or Ore numbers: numbers k such that the harmonic mean of the divisors of k is an integer. | [
"1",
"6",
"28",
"140",
"270",
"496",
"672",
"1638",
"2970",
"6200",
"8128",
"8190",
"18600",
"18620",
"27846",
"30240",
"32760",
"55860",
"105664",
"117800",
"167400",
"173600",
"237510",
"242060",
"332640",
"360360",
"539400",
"695520",
"726180",
"753480",
... | [
"nonn",
"nice"
] | 180 | 1 | 2 | [
"A000005",
"A000203",
"A000290",
"A001599",
"A001600",
"A003601",
"A007340",
"A007691",
"A027750",
"A035527",
"A053783",
"A074247",
"A090240",
"A090945"
] | [
"M4185",
"N1743"
] | N. J. A. Sloane | 2025-11-26T15:59:31 | oeisdata/seq/A001/A001599.seq | 5b2a35d9d9e66bb16d825694693b5da4 |
A001600 | Harmonic means of divisors of harmonic numbers. | [
"1",
"2",
"3",
"5",
"6",
"5",
"8",
"9",
"11",
"10",
"7",
"15",
"15",
"14",
"17",
"24",
"24",
"21",
"13",
"19",
"27",
"25",
"29",
"26",
"44",
"44",
"29",
"46",
"39",
"46",
"27",
"42",
"47",
"47",
"54",
"35",
"41",
"60",
"51",
"37",
"48",... | [
"nonn",
"nice",
"easy"
] | 49 | 1 | 2 | [
"A001599",
"A001600",
"A090240"
] | [
"M0609",
"N0220"
] | N. J. A. Sloane | 2025-11-05T15:35:23 | oeisdata/seq/A001/A001600.seq | 19e4d341d53880492c4ccf2fe46a44ef |
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