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 A100089 #10 Jun 23 2020 06:16:13
%S A100089 1,24,5040,3628800,6227020800,20922789888000,121645100408832000,
%T A100089 1124000727777607680000,15511210043330985984000000,
%U A100089 304888344611713860501504000000,8222838654177922817725562880000000
%N A100089 a(n) = (3*n+1)!.
%F A100089 Sum_{n>=0} 1/a(n) = A143820. - _Amiram Eldar_, Jun 23 2020
%p A100089 seq( (3*n+1)!,n=0..13);
%t A100089 Table[(3*n+1)!, {n, 0, 10}] (* _Amiram Eldar_, Jun 23 2020 *)
%Y A100089 Cf. A000142, A143820.
%K A100089 nonn
%O A100089 0,2
%A A100089 _Jorge Coveiro_, Dec 26 2004
%E A100089 Offset 0 and a(0) added by _Amiram Eldar_, Jun 23 2020