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 A068158 #10 Aug 19 2024 09:15:58 %S A068158 1,1,1,1,1,1,1,1,1,3628800,1,0,0,0,0,0,0,0,0,1216451004088320000, %T A068158 106661318400,1,0,0,0,0,0,0,0,44208809968698509772718080000000, %U A068158 1320509264105545113600000,10178348544000,1,0,0,0,0,0,0 %N A068158 a(n) = floor(n!/R(n)!), where R(n) = digit reversal of n (A004086). %C A068158 If n < R(n) then a(n) = 0. %C A068158 If n = R(n) then n is a palindrome and a(n) = 1. %C A068158 If n > R(n) then n!/R(n)! is an integer. %e A068158 a(21) = 21! / 12! = 51090942171709440000/479001600 = 106661318400. %o A068158 (PARI) a(n) = n!\fromdigits(Vecrev(digits(n)))!; \\ _Michel Marcus_, Aug 19 2024 %Y A068158 Cf. A004086. %K A068158 base,easy,nonn %O A068158 1,10 %A A068158 _Amarnath Murthy_, Feb 24 2002