OFFSET
1,9
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
FORMULA
G.f.: (1/Product_{k>=1} (1-x^k)) * Sum_{k>=1} (-1)^(k-1) * x^(4*k) * ( x^(k*(3*k-1)/2) - x^(k*(3*k+1)/2) ).
PROG
(PARI) my(N=60, x='x+O('x^N)); concat([0, 0, 0, 0], Vec(1/prod(k=1, N, 1-x^k)*sum(k=1, N, (-1)^(k-1)*x^(4*k)*(x^(k*(3*k-1)/2)-x^(k*(3*k+1)/2)))))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, May 21 2023
STATUS
approved