A119829 Diagonal sum of number triangle A119828.

1, 2, 25, 732, 40681, 3648990, 480817681, 87417943256, 20966398997041, 6412838733766170, 2436104066933508841, 1125217445576328664692, 621010503476937955204825, 403601732164215102065708342

Offset: 0

Author

Paul Barry, May 25 2006

Keywords

• easy
• nonn

Programs

Mathematica

Table[Sum[(2(n-k))!/(2k)!,{k,0,Floor[n/2]}],{n,0,20}] (* Harvey P. Dale, Aug 26 2024 *)

Formula

a(n)=sum{k=0..floor(n/2), (2(n-k))!/(2k)!}