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 A089501 #6 Jul 10 2015 05:21:04 %S A089501 1,6,2880,870912000,637129677864960000, %T A089501 3076276241856388273274880000000, %U A089501 218470761021769399142244567460557619200000000000,444747235963340607791337561259087696911923105885061120000000000000000 %N A089501 Built from superfactorials A000178. %C A089501 a(n) appears as a numerator in A089500. %F A089501 N(n) := sfac(n-1)*sfac(2*n+1)/sfac(n+1) with sfac(n) := product(k!, k=1..n), n>=1, sfac(0) := 1. sfac(n)= A000178(n). %F A089501 a(n) ~ 2^(2*n^2 + 5*n + 23/12) * n^(2*n^2 + 2*n -1/12) * Pi^n / (A * exp(3*n^2 + 2*n - 1/12)), where A = A074962 = 1.2824271291... is the Glaisher-Kinkelin constant. - _Vaclav Kotesovec_, Jul 10 2015 %K A089501 nonn,easy %O A089501 0,2 %A A089501 _Wolfdieter Lang_, Nov 07 2003