This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A052295 #19 Dec 07 2019 12:18:22 %S A052295 1,1,6,720,3628800,1307674368000,51090942171709440000, %T A052295 304888344611713860501504000000, %U A052295 371993326789901217467999448150835200000000,119622220865480194561963161495657715064383733760000000000,12696403353658275925965100847566516959580321051449436762275840000000000000 %N A052295 a(n) = (n*(n+1)/2)!. %C A052295 Factorials of triangular numbers. - _Harvey P. Dale_, Aug 13 2012 %H A052295 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 A052295 a(n) = A000142(A000217(n)). - _Henry Bottomley_, Jun 02 2000 %t A052295 Accumulate[Range[0,10]]! (* _Harvey P. Dale_, Aug 13 2012 *) %o A052295 (Sage) [(factorial(binomial(n,2))) for n in range(1, 15)] # _Zerinvary Lajos_, Nov 30 2009 %K A052295 nonn,easy %O A052295 0,3 %A A052295 Jeevan Chana Rai (Karanjit.Rai(AT)btinternet.com), Feb 09 2000 %E A052295 An incorrect formula was deleted by _N. J. A. Sloane_, Sep 21 2008