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 A274634 #10 Aug 18 2016 05:34:39
%S A274634 0,2,24,744,35160,2394720,222712560,27154350720,4205374225920,
%T A274634 806700010233600,187793061031699200,52162131258836121600,
%U A274634 17043501717850146739200,6471785359791584459827200,2826261760629911644744704000,1406604814631643298586923008000
%N A274634 a(n) = n!*A003436(n).
%H A274634 Vincenzo Librandi, <a href="/A274634/b274634.txt">Table of n, a(n) for n = 1..100</a>
%F A274634 a(n) ~ 2*sqrt(Pi*n)*2^n*n^(2*n)/exp(2*n+1). - _Ilya Gutkovskiy_, Aug 18 2016
%t A274634 a[n_]:= n! (2 n - 1)!! Hypergeometric1F1[-n, 1 - 2 n, - 2]; a[1] = 0; Table[a[n], {n, 1, 20}] (* _Vincenzo Librandi_, Aug 18 2016 *)
%Y A274634 Cf. A003436.
%K A274634 nonn
%O A274634 1,2
%A A274634 _N. J. A. Sloane_, Jul 08 2016