%I #8 Oct 08 2024 05:19:57
%S 1,1,4,8,13,20,32,52,84,133,204,304,444,636,900,1264,1761,2440,3364,
%T 4608,6276,8496,11424,15268,20284,26789,35196,46016,59884,77612,
%U 100204,128900,165260,211200,269072,341792,432917,546788,688728,865200,1084048,1354816,1689048
%N G.f.: Sum_{k>=0} x^(k^2) * Product_{j=1..k} ((1 + x^j)/(1 - x^j))^2.
%H Vaclav Kotesovec, <a href="/A376854/b376854.txt">Table of n, a(n) for n = 0..10000</a>
%F a(n) ~ (1 + sqrt(2)) * exp(Pi*sqrt(n)) / (2^(9/2) * n).
%t nmax = 60; CoefficientList[Series[Sum[x^(k^2) * Product[(1+x^j)/(1-x^j), {j, 1, k}]^2, {k, 0, Sqrt[nmax]}], {x, 0, nmax}], x]
%Y Cf. A066447, A000041, A216222, A376852, A376853.
%K nonn
%O 0,3
%A _Vaclav Kotesovec_, Oct 06 2024