%I #4 Aug 28 2015 03:16:23

%S 1,4,6,4,5,16,24,20,26,48,56,60,98,132,130,168,253,288,324,448,539,

%T 588,780,1000,1086,1304,1690,1916,2205,2812,3274,3648,4507,5396,6018,

%U 7200,8674,9680,11250,13616,15425,17532,20962,23988,26960,31868,36836,41164

%N Expansion of Product_{k>=0} (1+x^(3*k+1))^4.

%F a(n) ~ exp(2*Pi*sqrt(n)/3) / (2^(1/3) * sqrt(3) * n^(3/4)).

%t nmax=50; CoefficientList[Series[Product[(1+x^(3*k+1))^4, {k, 0, nmax}], {x, 0, nmax}], x]

%Y Cf. A261612, A261615, A261638.

%K nonn

%O 0,2

%A _Vaclav Kotesovec_, Aug 27 2015