A119649 a(0)=0, a(1)=1; for n >= 1, a(n+1) = (n+2)*a(n) + 2*Sum_{k=2..n-1} binomial(n, k)*a(k)*a(n-k+1).

0, 1, 3, 12, 114, 1404, 22968, 456408, 10762992, 292851648, 9038285280, 311858347968, 11896746473088, 497156854363776, 22586083785232128, 1108320770197398528, 58420751739908940288, 3292054745517600648192, 197491129333671926863872, 12566253138627465234487296

Offset: 0

Author

N. J. A. Sloane, Jul 30 2006

Keywords

• nonn

Comments

The recurrence for A000311, with slightly different initial conditions.

Links

• T. D. Noe, Table of n, a(n) for n = 0..100

Crossrefs

Cf. A000311.

Programs

Maple

M:=50; a:=array(0..100); a[0]:=0; a[1]:=1; lprint(0,a[0]); lprint(1,a[1]); for n from 1 to M do a[n+1]:=(n+2)*a[n]+2*add(binomial(n,k)*a[k]*a[n-k+1],k=2..n-1); lprint(n+1,a[n+1]); od: