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a(n) = [x^n] Product_{k=1..n} 1/(x^k*(1-x^k)^2).
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%I #5 Jun 11 2015 06:25:09

%S 1,3,20,158,1307,11352,102538,954904,9112038,88723163,878714118,

%T 8829998320,89848944237,924291213496,9600148608620,100565064076006,

%U 1061498376477423,11281275452880277,120635822090127386,1297256892395670322,14021436433125959714

%N a(n) = [x^n] Product_{k=1..n} 1/(x^k*(1-x^k)^2).

%F a(n) ~ c * d^n / n^(5/2), where d = 12.0708016857156441729965623654557363850943928675996965027830903372727... = r^3/(r-1)^2, where r is the root of the equation polylog(2, 1-r) + (3*log(r)^2)/4 = 0, c = 8.36819319541... .

%t Table[SeriesCoefficient[1/Product[x^k*(1-x^k)^2, {k, 1, n}], {x, 0, n}], {n, 0, 25}]

%t Table[SeriesCoefficient[1/Product[1-x^k, {k, 1, n}]^2, {x, 0, n*(n+3)/2}], {n, 0, 25}]

%Y Cf. A258788, A258789, A258793, A258794.

%K nonn

%O 0,2

%A _Vaclav Kotesovec_, Jun 10 2015