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 A254529 #13 Aug 20 2021 06:25:54 %S A254529 1,1,6,42,456,5640,93600,1728720,38344320,948931200,26555558400, %T A254529 817935148800,27735629644800,1020596255078400,40642432179148800, %U A254529 1737890081351424000,79498734605402112000,3871319396080840704000,200017645344178421760000,10925549584125028909056000 %N A254529 a(n) = n! * (number of mapping patterns on n). %C A254529 a(n) is the number of ordered pairs (p, f) such that p f = f p, where p is a permutation and f is an endofunction. %H A254529 Alois P. Heinz, <a href="/A254529/b254529.txt">Table of n, a(n) for n = 0..382</a> %H A254529 Math Overflow, <a href="http://mathoverflow.net/questions/143058/what-is-the-probability-two-random-maps-on-n-symbols-commute">What is the probability two random maps on n symbols commute?</a>, 2013. %F A254529 a(n) = n! * A001372(n). - _Joerg Arndt_, Feb 01 2015 %Y A254529 Cf. A001372, A053529, A181162. %K A254529 nonn,easy %O A254529 0,3 %A A254529 _Martin Fuller_, Feb 01 2015