OFFSET
0,2
FORMULA
a(n) ~ exp(2*Pi*sqrt(2*n)/3) * Gamma(1/3)^4 / (8 * 2^(1/12) * sqrt(3) * Pi^(8/3) * n^(5/12)).
MATHEMATICA
nmax=50; CoefficientList[Series[Product[1/(1-x^(3*k+1))^4, {k, 0, nmax}], {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Aug 27 2015
STATUS
approved