A107868 Column 0 of triangle A107867; a(n) = C( n*(n-1)/2 + n + 1, n).

1, 2, 6, 35, 330, 4368, 74613, 1560780, 38608020, 1101716330, 35607051480, 1285063345176, 51209646652255, 2232785266876080, 105710363656182600, 5399936810873056584, 295998326072989842600, 17328840976366636057110

Offset: 0

Author

Paul D. Hanna, Jun 04 2005

Keywords

• nonn

Crossrefs

Cf. A107867, A107869.

Programs

PARI

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