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%I #7 Sep 16 2021 23:53:10
%S 1,1,2,6,42,175,2015,10843,157388,1240377,20118077,172029231,
%T 4052166250,36360150385,952965601471,11194257455977,316421367496344,
%U 3722989943371217,134504815853036649,1641201826969536379,67298415781492985366,935342610632498431241,40176825083871581430723
%N E.g.f.: Product_{k>=1} 1 / (1 - x^k)^exp(-x).
%C Exponential transform of A002743.
%C The first negative term is a(71) = -1.2234788... * 10^104.
%F E.g.f.: exp( exp(-x) * Sum_{k>=1} sigma(k) * x^k / k ).
%F a(0) = 1; a(n) = Sum_{k=1..n} binomial(n-1,k-1) * A002743(k) * a(n-k).
%t nmax = 22; CoefficientList[Series[Product[1/(1 - x^k)^Exp[-x], {k, 1, nmax}], {x, 0, nmax}], x] Range[0, nmax]!
%t nmax = 22; CoefficientList[Series[Exp[Exp[-x] Sum[DivisorSigma[1, k] x^k/k, {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!
%t A002743[n_] := Sum[(-1)^(n - k) Binomial[n, k] DivisorSigma[1, k] (k - 1)!, {k, 1, n}]; a[0] = 1; a[n_] := a[n] = Sum[Binomial[n - 1, k - 1] A002743[k] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 22}]
%Y Cf. A000203, A002743, A053529, A346545, A346546, A346547.
%K sign
%O 0,3
%A _Ilya Gutkovskiy_, Sep 16 2021