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

%S 6,120,2340,49315,1142932,29141994,814059798,24779916843,817506518829,

%T 29081010732059,1110248649302494,45298134089851175,

%U 1967550159430960784,90668183653348456484,4418855084158930131012,227122154996245283660487

%N Column 2 of triangle A185755.

%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+2, A=subst(G, x, A+O(x^(n+3))));polcoeff(polcoeff(A, n+2,x),2,y)}

%Y Cf. A185755, A185756, A185758, A185759.

%K nonn

%O 1,1

%A _Paul D. Hanna_, Feb 03 2011