A072331 a(n) = 2^(n-1) * Sum_{k=0..n} ((n+k)!/(n-k)!)/k!.

3, 38, 772, 21768, 786736, 34703456, 1807726656, 108602413184, 7392195003136, 562241229891072, 47257832090862592, 4349969517278922752, 435185983056255725568, 47017486048144734052352

Offset: 1

Author

Benoit Cloitre, Jul 31 2002

Keywords

• easy
• nonn

Crossrefs

Cf. A001517.

Programs

Mathematica

Table[2^(n-1) Sum[((n+k)!/(n-k)!)/k!,{k,0,n}],{n,15}] (* Harvey P. Dale, May 22 2012 *)

Extensions

Definition clarified by Harvey P. Dale, May 22 2012