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 A161563 #7 May 03 2025 15:21:22
%S A161563 1,1,2,6,40320,1307674368000,
%T A161563 12413915592536072670862289047373375038521486354677760000000000
%N A161563 Factorials of double factorials.
%C A161563 As of version 7, Mathematica parses n!!! as (n!!)!. This sequence is not to be confused with the triple factorials A007661 or A161474 which are usually denoted n!!!.
%t A161563 lst={};Do[AppendTo[lst,n!!! ],{n,0,9}];lst
%t A161563 (* alternatively *) Array[ #!!!&,9,0]
%K A161563 nonn
%O A161563 0,3
%A A161563 _Vladimir Joseph Stephan Orlovsky_, Jun 13 2009
%E A161563 Corrected by _Charles R Greathouse IV_, Nov 11 2009
%E A161563 Offset set to 0 by _Alois P. Heinz_, Jan 12 2022