A107872 Column 1 of triangle A107870; a(n) = C(n*(n+1)/2 + n+2, n).

1, 4, 21, 165, 1820, 26334, 475020, 10295472, 260932815, 7575968400, 247994680648, 9036996468045, 362827605867363, 15913388077274800, 757000487505568680, 38819452599736372800, 2134712294190092847615

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Maple

A107872:=n->binomial(n*(n+1)/2+n+2, n): seq(A107872(n), n=0..20); # Wesley Ivan Hurt, Aug 09 2014

Mathematica

Table[Binomial[(n(n+1))/2+n+2, n], {n, 0, 20}] (* Harvey P. Dale, Aug 09 2014 *)

Prog

(PARI) a(n)=binomial(n*(n+1)/2+n+2, n)
(Magma) [Binomial((n^2+3*n+4) div 2, n): n in [0..20]] // Vincenzo Librandi, Aug 09 2014

Crossrefs

Cf. A107870, A107871.

Sequence in context: A366184 A179496 A339233 * A008858 A217484 A078670

Adjacent sequences: A107869 A107870 A107871 * A107873 A107874 A107875

Keyword

nonn

Author

Paul D. Hanna, Jun 04 2005

Status

approved