A386467 a(0) = a(1) = 1; a(n) = a(n-1) + a(n-2) + Sum_{k=0..n-1} k * a(k) * a(n-1-k).
1, 1, 3, 11, 56, 353, 2619, 22175, 210077, 2196732, 25104008, 311139385, 4156661566, 59551385285, 910955221547, 14821776943015, 255639834413712, 4659720389150655, 89515541970546889, 1807824383345511646, 38294715773270374886, 849051935815301595992, 19665430140710069083996
Offset: 0
Keywords
Programs
-
PARI
a_vector(n) = my(v=vector(n+1, i, if(i<=2, 1, 0))); for(i=2, n, v[i+1]=v[i]+v[i-1]+sum(j=0, i-1, j*v[j+1]*v[i-j])); v;
Formula
G.f. A(x) satisfies A(x) = 1/( 1 - x - x^2 - x^2 * (d/dx A(x)) ).