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%I #19 Dec 07 2019 12:18:22
%S 1,1,6,720,3628800,1307674368000,51090942171709440000,
%T 304888344611713860501504000000,
%U 371993326789901217467999448150835200000000,119622220865480194561963161495657715064383733760000000000,12696403353658275925965100847566516959580321051449436762275840000000000000
%N a(n) = (n*(n+1)/2)!.
%C Factorials of triangular numbers. - _Harvey P. Dale_, Aug 13 2012
%H Christian Gaetz, Yibo Gao, <a href="https://arxiv.org/abs/1905.00047">Padded Schubert polynomials and weighted enumeration of Bruhat chains</a>, arXiv:1905.00047 [math.CO], 2019. This sequence but shifted: f(n) = binomial(n, 2)!.
%F a(n) = A000142(A000217(n)). - _Henry Bottomley_, Jun 02 2000
%t Accumulate[Range[0,10]]! (* _Harvey P. Dale_, Aug 13 2012 *)
%o (Sage) [(factorial(binomial(n,2))) for n in range(1, 15)] # _Zerinvary Lajos_, Nov 30 2009
%K nonn,easy
%O 0,3
%A Jeevan Chana Rai (Karanjit.Rai(AT)btinternet.com), Feb 09 2000
%E An incorrect formula was deleted by _N. J. A. Sloane_, Sep 21 2008
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