OFFSET
0,3
FORMULA
a(n) = [x^n] 1/(1 - x - n^3*x^2).
a(n) ~ n^(3*n/2) if n is even and a(n) ~ n^((3*n-1)/2)/2 if n is odd. - Vaclav Kotesovec, Jan 09 2024
MATHEMATICA
Table[Hypergeometric2F1[1/2 - n/2, -n/2, -n, -4*n^3], {n, 0, 20}] (* Vaclav Kotesovec, Jan 09 2024 *)
PROG
(PARI) a(n) = sum(k=0, n\2, n^(3*k)*binomial(n-k, k));
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Jan 09 2024
STATUS
approved