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E.g.f. satisfies: A(x) = exp(x) * A(x^2)*A(x^3)*A(x^4)*...*A(x^n)*...
6

%I #9 Nov 04 2018 09:28:55

%S 1,1,3,13,97,621,6571,58633,779073,9317017,138628531,1977676581,

%T 37384244833,620735382853,12434855135067,245117537189281,

%U 5651550278494081,123266430844431153,3128700944169196003

%N E.g.f. satisfies: A(x) = exp(x) * A(x^2)*A(x^3)*A(x^4)*...*A(x^n)*...

%H Vaclav Kotesovec, <a href="/A129375/b129375.txt">Table of n, a(n) for n = 0..260</a>

%F E.g.f.: A(x) = exp( Sum_{n>=1} A074206(n)*x^n ) where A074206(n) equals the number of ordered factorizations of n.

%F a(n) ~ n! * exp(2/5 + (1 + 1/r) * (-Gamma(1+r) / Zeta'(r))^(1/(1+r)) * n^(r/(1+r))) * (-Gamma(1+r) / Zeta'(r))^(1/(2*(1+r))) / (sqrt(2*Pi*(1+r)) * n^((2+r)/(2*(1+r)))), where r = A107311 = 1.7286472389981836181351... is the root of the equation Zeta(r) = 2, Zeta'(r) = -1/A247667. - _Vaclav Kotesovec_, Nov 04 2018

%o (PARI) {a(n)=local(A=1+x);for(i=2,n,A=exp(x+x*O(x^n))*prod(n=2,i,subst(A,x,x^n+x*O(x^i)))); n!*polcoeff(A,n)}

%Y Cf. A074206, A129373, A129374.

%K nonn

%O 0,3

%A _Paul D. Hanna_, Apr 12 2007

%E PARI program fixed by _Vaclav Kotesovec_, Feb 26 2014