OFFSET
0,5
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..10000
MATHEMATICA
nmax = 50; CoefficientList[Series[Product[(1 + x^(3*k))^(3*k) / (1 + x^k)^k, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Apr 16 2017 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Apr 16 2017
STATUS
approved