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Expansion of e.g.f. Product_{k>=1} (1 + (exp(x)-1)^(k^2)) / (1 - (exp(x)-1)^(k^2)).
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%I #13 Mar 08 2024 12:00:07

%S 1,2,6,26,198,2042,22566,259226,3249798,47156282,799108326,

%T 15116875226,305203728198,6488119430522,146602455461286,

%U 3557921474016026,92563621667899398,2554423824661976762,74142584637465337446,2258422219660738881626,72255096004023644467398

%N Expansion of e.g.f. Product_{k>=1} (1 + (exp(x)-1)^(k^2)) / (1 - (exp(x)-1)^(k^2)).

%C Convolution of A306082 and A306083.

%H Vaclav Kotesovec, <a href="/A306147/b306147.txt">Table of n, a(n) for n = 0..420</a>

%F a(n) = Sum_{k=0..n} Stirling2(n,k) * A103265(k) * k!.

%F a(n) ~ n! * ((2*sqrt(2) - 1) * Zeta(3/2))^(2/3) * exp(3 * (Pi/log(2))^(1/3) * ((2*sqrt(2) - 1) * Zeta(3/2))^(2/3) * n^(1/3) / 4) / (8 * sqrt(3) * Pi^(7/6) * n^(7/6) * (log(2))^(n - 1/6)).

%t nmax = 20; CoefficientList[Series[Product[(1 + (Exp[x] - 1)^(k^2)) / (1 - (Exp[x] - 1)^(k^2)), {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, nmax]!

%Y Cf. A001156, A033461, A103265, A306082, A306083.

%K nonn

%O 0,2

%A _Vaclav Kotesovec_, Jun 23 2018