OFFSET
0,7
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..10000
FORMULA
a(n) is sum of i^2 * j^2 * k^2 for positive integers i,j,k such that i^2+j^2+k^2=n.
PROG
(PARI) a(n) = sum(i=1, n, sum(j=1, n, sum(k=1, n, (i^2+j^2+k^2==n)*(i*j*k)^2)));
(PARI) my(N=66, x='x+O('x^N)); concat([0, 0, 0], Vec(sum(k=0, sqrtint(N), k^2*x^k^2)^3))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Sep 14 2021
STATUS
approved