A052295 a(n) = (n*(n+1)/2)!.

1, 1, 6, 720, 3628800, 1307674368000, 51090942171709440000, 304888344611713860501504000000, 371993326789901217467999448150835200000000, 119622220865480194561963161495657715064383733760000000000, 12696403353658275925965100847566516959580321051449436762275840000000000000

Offset: 0

Author

Jeevan Chana Rai (Karanjit.Rai(AT)btinternet.com), Feb 09 2000

Keywords

• nonn
• easy

Comments

Factorials of triangular numbers. - Harvey P. Dale, Aug 13 2012

Links

• Christian Gaetz, Yibo Gao, Padded Schubert polynomials and weighted enumeration of Bruhat chains, arXiv:1905.00047 [math.CO], 2019. This sequence but shifted: f(n) = binomial(n, 2)!.

Programs

Mathematica

Accumulate[Range[0,10]]! (* Harvey P. Dale, Aug 13 2012 *)

Sage

[(factorial(binomial(n,2))) for n in range(1, 15)] # Zerinvary Lajos, Nov 30 2009

Formula

a(n) = A000142(A000217(n)). - Henry Bottomley, Jun 02 2000

Extensions

An incorrect formula was deleted by N. J. A. Sloane, Sep 21 2008