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 A004153 #23 Dec 28 2023 07:07:57
%S A004153 1,1,2,6,42,21,27,405,2304,88263,88263,861993,6100974,80207226,
%T A004153 219287178,8634767031,88898722902,690824786553,8275073732046,
%U A004153 238804001546121,466718002092342,4490717124909015,867067777270004211,4667948883761025852,63934932337104844026
%N A004153 Factorial numbers written backwards.
%H A004153 Alois P. Heinz, <a href="/A004153/b004153.txt">Table of n, a(n) for n = 0..500</a>
%F A004153 a(n) = A004086(A000142(n)). - _Michel Marcus_, Apr 05 2014
%p A004153 a:= n-> (s-> parse(cat(s[-i]$i=1..length(s))))(""||(n!)):
%p A004153 seq(a(n), n=0..30); # _Alois P. Heinz_, Apr 09 2015
%o A004153 (PARI) reverse(expr)=my(v=Vec(Str(expr)),n=length(v));eval(concat(vector(n,i,v[n-i+1])));
%o A004153 a(n) = reverse(n!); \\ _Michel Marcus_, Apr 05 2014
%Y A004153 Cf. A000142, A004086, A004192.
%K A004153 nonn,base
%O A004153 0,3
%A A004153 _N. J. A. Sloane_
%E A004153 More terms from _Eric M. Schmidt_, Apr 04 2014