A132788 a(n) = 2*binomial(2*n,n)/(n+1) - n.

1, 2, 7, 24, 79, 258, 851, 2852, 9715, 33582, 117561, 416012, 1485787, 5348866, 19389675, 70715324, 259289563, 955277382, 3534526361, 13128240820, 48932534019, 182965127258, 686119227277, 2579808294624, 9723892802879, 36734706144278, 139067101831981

Offset: 1

Author

Gary W. Adamson, Aug 30 2007

Keywords

• nonn

Examples

			a(4) = 24 = sum of row 4 terms of triangle A132787: (1 + 11 + 11 + 1).
		

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..200

Crossrefs

Row sums of A132787.

Cf. A000108 (Catalan numbers).

Programs

Mathematica

Table[2Binomial[2n,n]/(n+1)-n,{n,27}] (* James C. McMahon, Mar 08 2025 *)

PARI

a(n) = 2*binomial(2*n,n)/(n+1) - n; \\ Andrew Howroyd, Aug 10 2018

Formula

a(n) = 2*A000108(n) - n. - Andrew Howroyd, Aug 10 2018

Extensions

Name changed, a(8) corrected and a(11)-a(27) from Andrew Howroyd, Aug 10 2018