OFFSET
0,7
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..185
FORMULA
G.f.: Sum_{k>=0} (k^3 * x)^(3 * k) / (1 - k^3 * x).
MATHEMATICA
a[0] = 1; a[n_] := Sum[k^(3*n), {k, 0, Floor[n/3]}]; Array[a, 16, 0] (* Amiram Eldar, Apr 13 2022 *)
PROG
(PARI) a(n) = sum(k=0, n\3, k^(3*n));
(PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k^3*x)^(3*k)/(1-k^3*x)))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Apr 13 2022
STATUS
approved