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Expansion of Product_{k>=1} (1 + x^k) * (1 + x^(2*k)) * (1 + x^(3*k)).
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%I #7 Aug 17 2019 02:38:20

%S 1,1,2,4,5,8,13,17,24,36,47,64,89,115,152,204,260,336,438,552,702,896,

%T 1117,1400,1758,2171,2688,3332,4079,5000,6131,7446,9048,10992,13255,

%U 15984,19264,23081,27644,33084,39408,46912,55797,66107,78264,92572,109140

%N Expansion of Product_{k>=1} (1 + x^k) * (1 + x^(2*k)) * (1 + x^(3*k)).

%H Vaclav Kotesovec, <a href="/A327045/b327045.txt">Table of n, a(n) for n = 0..10000</a>

%F a(n) ~ 11^(1/4) * exp(sqrt(11*n/2)*Pi/3) / (2^(13/4)*sqrt(3)*n^(3/4)).

%t nmax = 50; CoefficientList[Series[Product[(1+x^k) * (1+x^(2*k)) * (1+x^(3*k)), {k, 1, nmax}], {x, 0, nmax}], x]

%Y Cf. A000009, A001935, A327046, A327047.

%Y Cf. A107742, A327042.

%K nonn

%O 0,3

%A _Vaclav Kotesovec_, Aug 16 2019