A107871 Column 0 of triangle A107870; a(n) = C( n*(n-1)/2 + n+2, n).

1, 3, 10, 56, 495, 6188, 100947, 2035800, 48903492, 1362649145, 43183019880, 1533058025824, 60246643120300, 2595612872743443, 121623751733457400, 6156937298378625264, 334817778672726215400, 19463553270556728904725

Offset

0,2

Links

Table of n, a(n) for n=0..17.

Prog

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

Crossrefs

Cf. A107870, A107872.

Sequence in context: A301920 A203416 A002218 * A111270 A307906 A366696

Adjacent sequences: A107868 A107869 A107870 * A107872 A107873 A107874

Keyword

nonn

Author

Paul D. Hanna, Jun 04 2005

Status

approved