%I #19 May 30 2018 13:56:57
%S 1,4,14,48,141,396,1058,2696,6646,15884,36956,83976,186849,407864,
%T 875030,1847824,3845520,7895872,16010610,32088120,63611656,124817444,
%U 242560418,467095640,891754784,1688619460
%N Expansion of Product_{m>=1} (1+q^m)^(4*m).
%C In general, if g.f. = Product_{m>=1} (1+x^m)^(t*m) and t>=1, then a(n) ~ 2^(-2/3 - t/12) * exp((3/2)^(4/3) * t^(1/3) * Zeta(3)^(1/3) * n^(2/3)) * t^(1/6) * Zeta(3)^(1/6) / (3^(1/3) * sqrt(Pi) * n^(2/3)). - _Vaclav Kotesovec_, Aug 17 2015
%H Seiichi Manyama, <a href="/A027906/b027906.txt">Table of n, a(n) for n = 0..10000</a>
%H Vaclav Kotesovec, <a href="http://arxiv.org/abs/1509.08708">A method of finding the asymptotics of q-series based on the convolution of generating functions</a>, arXiv:1509.08708 [math.CO], Sep 30 2015, p. 19.
%F a(n) ~ exp(2^(-2/3) * 3^(4/3) * Zeta(3)^(1/3) * n^(2/3)) * Zeta(3)^(1/6) / (2^(2/3) * 3^(1/3) * sqrt(Pi) * n^(2/3)). - _Vaclav Kotesovec_, Aug 17 2015
%F G.f.: exp(4*Sum_{k>=1} (-1)^(k+1)*x^k/(k*(1 - x^k)^2)). - _Ilya Gutkovskiy_, May 30 2018
%t nmax = 40; CoefficientList[Series[Product[(1+x^k)^(4*k), {k, 1, nmax}], {x, 0, nmax}], x] (* _Vaclav Kotesovec_, Aug 17 2015 *)
%Y Cf. A026007 (t=1), A026011 (t=2), A027346 (t=3).
%K nonn
%O 0,2
%A _N. J. A. Sloane_