A123491 Diagonal sums of number triangle A123490.

1, 2, 5, 10, 22, 48, 112, 274, 715, 1982, 5837, 18180, 59644, 205296, 739032, 2775180, 10846965, 44039754, 185391469, 807776198, 3637193474, 16900721824, 80939650552, 399061251246, 2023408865983, 10540656630118

Offset

0,2

Links

G. C. Greubel, Table of n, a(n) for n = 0..675

Formula

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

Mathematica

Table[Sum[((k + 2)^(n - 2 k) + k)/(k + 1), {k, 0, Floor[n/2]}], {n, 0, 50}] (* G. C. Greubel, Oct 14 2017 *)

Prog

(PARI) for(n=0, 25, print1(sum(k=0, floor(n/2), ((k + 2)^(n - 2 k) + k)/(k + 1)), ", ")) \\ G. C. Greubel, Oct 14 2017

Crossrefs

Cf. A123490.

Sequence in context: A320650 A018109 A341020 * A329185 A232163 A166300

Adjacent sequences: A123488 A123489 A123490 * A123492 A123493 A123494

Keyword

easy,nonn

Author

Paul Barry, Oct 01 2006

Status

approved