A107874 Column 0 of triangle A107873; a(n) = C( n*(n-1)/2 + n+3, n).

1, 4, 15, 84, 715, 8568, 134596, 2629575, 61523748, 1677106640, 52179482355, 1823810410032, 70724320184700, 3012192716517082, 139737927523546800, 7012067478708989884, 378371310857796292200, 21843987843214746108900

Offset

0,2

Links

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

Mathematica

Table[Binomial[(n(n-1))/2+n+3, n], {n, 0, 20}] (* Harvey P. Dale, Oct 05 2019 *)

Prog

(PARI) a(n)=binomial(n*(n-1)/2+n+3, n)

Crossrefs

Cf. A107873, A107875.

Sequence in context: A130679 A243048 A375633 * A237627 A034496 A079155

Adjacent sequences: A107871 A107872 A107873 * A107875 A107876 A107877

Keyword

nonn

Author

Paul D. Hanna, Jun 04 2005

Status

approved