A185756 - OEIS

%I #4 Mar 30 2012 18:37:26

%S 2,15,154,1995,31191,571221,11992688,283976517,7487521975,

%T 217567092743,6907888374828,237951469523807,8838510559556783,

%U 352160268261051113,14982705940607112640,677935029521206050505,32508195354031791206799

%N  Column 1 of triangle A185755.

%C  Column 0 of triangle A185755 equals n^(n-1).

%C A185755(n,k) equals the coefficient of x^n*y^k in the n-th iteration of x*(1+xy)/(1-x).

%o  (PARI) {a(n)=local(A=x, G=x*(1+x*y)/(1-x)); for(i=1, n+1, A=subst(G, x, A+O(x^(n+2))));polcoeff(polcoeff(A, n+1,x),1,y)}

%Y  Cf. A185755, A185757, A185758, A185759.

%K nonn

%O 1,1

%A _Paul D. Hanna_, Feb 03 2011