A291286 a(0)=1, a(1)=2, thereafter a(n) = n*a(n-1)+(n-1)*(n-2)*a(n-2).

1, 2, 4, 16, 88, 632, 5552, 57824, 695776, 9500128, 145097152, 2451080192, 45373649024, 913400022656, 19865889564928, 464227147597312, 11599471170191872, 308605525316616704, 8709955613991289856, 259922447412719218688, 8177253768239405504512

Offset

0,2

Links

Table of n, a(n) for n=0..20.

Maple

f:=proc(n) option remember;
if n <= 1 then n+1 else
n*f(n-1)+(n-1)*(n-2)*f(n-2); fi; end;
[seq(f(n), n=0..40)];

Crossrefs

A244430 and A291287 have the same recurrence.

Sequence in context: A212432 A351287 A013115 * A007171 A058136 A156335

Adjacent sequences: A291283 A291284 A291285 * A291287 A291288 A291289

Keyword

nonn

Author

N. J. A. Sloane, Aug 27 2017

Status

approved