OFFSET
0,2
FORMULA
a(n) ~ exp(Pi*sqrt(n)) * Gamma(1/3)^3 / (4 * Pi^2 * sqrt(3*n)).
MATHEMATICA
nmax=60; CoefficientList[Series[Product[((1+x^(3*k+1))/(1-x^(3*k+1)))^3, {k, 0, nmax}], {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Aug 28 2015
STATUS
approved