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%I #6 Sep 06 2018 17:35:10
%S 1,2,4,10,20,42,80,154,288,522,940,1658,2892,4970,8456,14218,23696,
%T 39122,64044,104042,167732,268602,427248,675482,1061632,1659298,
%U 2579676,3990418,6142892,9412906,14360136,21814698,33004704,49739426,74677924,111713658
%N Expansion of Product_{k>=1} ((1 + x^k)/(1 - x^k))^phi(k), where phi is the Euler totient function A000010.
%C Convolution of A299069 and A061255.
%H Vaclav Kotesovec, <a href="/A318975/b318975.txt">Table of n, a(n) for n = 0..1000</a>
%e a(n) ~ exp(3^(4/3) * (7*Zeta(3))^(1/3) * n^(2/3) / (2*Pi^(2/3)) - 1/6) * A^2 * (7*Zeta(3))^(1/9) / (sqrt(2) * 3^(7/18) * Pi^(8/9) * n^(11/18)), where A is the Glaisher-Kinkelin constant A074962.
%t nmax = 40; CoefficientList[Series[Product[((1+x^k)/(1-x^k))^EulerPhi[k], {k, 1, nmax}], {x, 0, nmax}], x]
%Y Cf. A061255, A299069, A301554, A301555.
%Y Cf. A318976, A318814, A318977.
%K nonn
%O 0,2
%A _Vaclav Kotesovec_, Sep 06 2018