OFFSET
0,3
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..1550
FORMULA
a(n) ~ c * 3^(4*n/3), where
c = 27.2472595510480930563087281042486261391960582835336715327... if n mod 3 = 0
c = 26.8841208067599453033952496040472485838861626762931432887... if n mod 3 = 1
c = 26.9277867007233095885556073185206409643421012262073908850... if n mod 3 = 2.
G.f.: exp(Sum_{k>=1} Sum_{j>=1} j^(4*k)*x^(j*k)/k). - Ilya Gutkovskiy, Jun 14 2018
MATHEMATICA
nmax = 40; CoefficientList[Series[Product[1/(1 - k^4*x^k), {k, 1, nmax}], {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Dec 16 2015
STATUS
approved