A110182 Diagonal sums of number triangle A110180.

1, 1, 2, 2, 5, 9, 26, 66, 199, 575, 1790, 5542, 17945, 58733, 198880, 685296, 2429281, 8778321, 32491940, 122503412, 471379771, 1844669495, 7346727298, 29712688698, 122054603983, 508548201863, 2149211636944, 9204566602696, 39944636660655

Offset: 0

Author

Paul Barry, Jul 14 2005

Keywords

• easy
• nonn

Formula

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