A104880 Diagonal sums of a sum-of-powers triangle.

1, 1, 2, 3, 5, 8, 14, 26, 53, 117, 280, 721, 1989, 5844, 18188, 59652, 205305, 739041, 2775190, 10846975, 44039765, 185391480, 807776210, 3637193486, 16900721837, 80939650565, 399061251260, 2023408865997, 10540656630133, 56362743769012

Offset: 0

Author

Paul Barry, Mar 28 2005

Keywords

• easy
• nonn

Comments

Diagonal sums of A104878.

Formula

a(0)=1, a(1)=1, a(n)=n+sum{k=2..floor(n/2), (k^(n-2k+1)-1)/(k-1)}, n>1.