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

1,2

Links

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

Formula

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

Example

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

Prog

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

Crossrefs

Row sums of A132787.

Cf. A000108 (Catalan numbers).

Sequence in context: A129020 A024024 A027122 * A109682 A215694 A027124

Adjacent sequences: A132785 A132786 A132787 * A132789 A132790 A132791

Keyword

nonn

Author

Gary W. Adamson, Aug 30 2007

Extensions

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

Status

approved