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Expansion of Product_{k>=1} ((1 + k*x^k)/(1 - k*x^k)).
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%I #11 Dec 17 2015 06:38:20

%S 1,2,6,16,38,88,200,428,902,1874,3780,7504,14732,28368,54052,101960,

%T 189750,349996,640218,1159624,2084952,3722008,6593560,11606268,

%U 20308188,35312170,61065636,105060200,179795936,306244136,519291476,876554860,1473504846

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

%C Convolution of A022629 and A006906.

%H Vaclav Kotesovec, <a href="/A265758/b265758.txt">Table of n, a(n) for n = 0..5000</a>

%F a(n) ~ c * 3^(n/3), where

%F c = 28711548.45004804552683870974706458425598... if mod(n,3) = 0

%F c = 28711547.74098394497470795294574937283075... if mod(n,3) = 1

%F c = 28711547.58138731567204220029302329316039... if mod(n,3) = 2.

%t nmax = 40; CoefficientList[Series[Product[(1 + k*x^k)/(1 - k*x^k), {k, 1, nmax}], {x, 0, nmax}], x]

%Y Cf. A006906, A015128, A022629, A022661, A022693, A261584.

%K nonn

%O 0,2

%A _Vaclav Kotesovec_, Dec 15 2015