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GCD
Given the value of N, you will have to find the value of G. The definition of G is given below:
G =
i<N
∑
i=1
j≤N
∑
j=i+1
GCD(i, j)
Here GCD(i, j) means the greatest common divisor of integer i and integer j.
For those who have trouble understanding summation notation, the meaning of G is given in the
following code:
G=0;
for(i=1;i<N;i++)
for(j=i+1;j<=N;j++)
{
G+=GCD(i,j);
}
/*Here GCD() is a function that finds
the greatest common divisor of the two
input numbers*/
Input
The input file contains at most 100 lines of inputs. Each line contains an integer N (1 < N < 501).
The meaning of N is given in the problem statement. Input is terminated by a line containing a single
zero. This zero should not be processed.
Output
For each line of input produce one line of output. This line contains the value of G for corresponding
N.
Sample Input
10
100
500
0
Sample Output
67
13015
442011