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 A155813 a(n) = [x^(n+1)*y] exp( Sum_{m>=1} (3^m + y)^m * x^m/m ), in which the coefficients of x^n*y^k are integer for n>=k>=0. 1

%I #2 Mar 30 2012 18:37:16

%S 1,12,801,540720,3499254081,206071208583660,109444624780070083617,

%T 523382147212408702381556928,22528830325874782877760713232652641,

%U 8728012905287889947187989190298586968026540

%N a(n) = [x^(n+1)*y] exp( Sum_{m>=1} (3^m + y)^m * x^m/m ), in which the coefficients of x^n*y^k are integer for n>=k>=0.

%F Column 1 of triangle A155812.

%o (PARI) {a(n)=polcoeff(polcoeff(exp(sum(m=1,n+1,(3^m+y)^m*x^m/m)+x*O(x^(n+1))),n+1,x),1,y)}

%Y Cf. A155812.

%K nonn

%O 0,2

%A _Paul D. Hanna_, Feb 04 2009

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Last modified December 7 14:37 EST 2023. Contains 367656 sequences. (Running on oeis4.)