A185759 A diagonal of triangle A185755.

9, 154, 2340, 38325, 704102, 14570976, 337738758, 8697532008, 246819113442, 7660379273261, 258275171344333, 9403520522325228, 367786323703199388, 15381080863799688012, 684987041358431417024, 32366520461834117146792

Offset: 1

Author

Paul D. Hanna, Feb 03 2011

Keywords

• nonn

Comments

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

Crossrefs

Cf. A185755, A185756, A185757, A185758.

Programs

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),n-1,y)}