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

0,3

Comments

Diagonal sums of A104878.

Links

Table of n, a(n) for n=0..29.

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.

Crossrefs

Sequence in context: A212657 A065955 A196118 * A152478 A102973 A371992

Adjacent sequences: A104877 A104878 A104879 * A104881 A104882 A104883

Keyword

easy,nonn

Author

Paul Barry, Mar 28 2005

Status

approved