A228509 a(n) = binomial(n^2+n+1,n) * (n+1) / (n^2+n+1) for n>=0.

1, 2, 9, 88, 1425, 32886, 992446, 37106784, 1657248417, 86128357150, 5107663394691, 340427678198400, 25194445531808735, 2050156960934135340, 181938723871328671500, 17487609556155439051136, 1809886850192627028383553, 200670984392566362698014110, 23730570474434159458296269953

Offset

0,2

Links

Table of n, a(n) for n=0..18.

Formula

a(n) = (n+1)*A135862(n).

Example

G.f.: A(x) = 1 + 2*x + 9*x^2 + 88*x^3 + 1425*x^4 + 32886*x^5 +...

Mathematica

Table[(Binomial[n^2+n+1, n](n+1))/(n^2+n+1), {n, 0, 20}] (* Harvey P. Dale, Oct 13 2015 *)

Prog

(PARI) {a(n)=binomial(n^2+n+1, n)*(n+1)/(n^2+n+1)}
for(n=0, 20, print1(a(n), ", "))

Crossrefs

Cf. A135862, A135860.

Sequence in context: A259794 A347013 A132431 * A361607 A001192 A006120

Adjacent sequences: A228506 A228507 A228508 * A228510 A228511 A228512

Keyword

nonn

Author

Paul D. Hanna, Aug 23 2013

Status

approved