OFFSET
0,2
COMMENTS
In general, if g.f. = 1/(1-x)^m * Product_{k>=1} (1 + x^k), then a(n) ~ 2^(m - 2) * 3^(m/2 - 1/4) * n^(m/2 - 3/4) * exp(Pi*sqrt(n/3)) / Pi^m.
FORMULA
a(n) ~ 4 * 3^(7/4) * n^(5/4) * exp(Pi*sqrt(n/3)) / Pi^4.
MATHEMATICA
nmax = 50; CoefficientList[Series[(1/(1-x)^4 * Product[1+x^k, {k, 1, nmax}]), {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, May 28 2019
STATUS
approved