OFFSET
0,7
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: Sum_{j>=0} [z^j] Product_{k>=1} (1 + z*q^(3*j*k)/(1-q^k)).
PROG
(PARI) my(N=80, q='q+O('q^N)); Vec(sum(j=0, N, polcoef(prod(k=1, N, 1+z*q^(3*j*k)/(1-q^k)), j, z)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 13 2026
STATUS
approved
