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 A320244 G.f.: Product_{k>=1, j>=1} (1 + x^(k*j))^2 / (1 - x^(k*j)). 1

%I #7 Oct 08 2018 10:16:24

%S 1,3,10,28,72,172,397,867,1840,3783,7580,14829,28454,53540,99119,

%T 180676,324758,576145,1010051,1750782,3003386,5101769,8586891,

%U 14327582,23711567,38937304,63471475,102741924,165204561,263956121,419183458,661833319,1039140705

%N G.f.: Product_{k>=1, j>=1} (1 + x^(k*j))^2 / (1 - x^(k*j)).

%C Convolution of A006171 and A320235.

%H Vaclav Kotesovec, <a href="/A320244/b320244.txt">Table of n, a(n) for n = 0..10000</a>

%F Conjecture: log(a(n)) ~ Pi * sqrt(2*n*log(n)/3).

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

%Y Cf. A006171, A320235, A320238.

%K nonn

%O 0,2

%A _Vaclav Kotesovec_, Oct 08 2018

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