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 A239836 #17 Jan 29 2025 21:59:27 %S A239836 1,1,2,6,48,360,2880,20160,241920,3265920,47174400,678585600, %T A239836 12933043200,193037644800,3661488230400,74537438976000, %U A239836 1736591560704000,36991492521984000 %N A239836 Number of ordered pairs of permutation functions f,g on a size n set where f(g(g(x))) = g(f(f(x))). %F A239836 a(n) = A255525(n) * n!. %Y A239836 Cf. A000012, A000085, A000142, A088311, A053529, A001044, A239779, A255525. %K A239836 nonn,more %O A239836 0,3 %A A239836 _Chad Brewbaker_, Mar 27 2014 %E A239836 a(8)-a(9) from _Giovanni Resta_, Mar 27 2014 %E A239836 a(10)-a(16) from _Max Alekseyev_, Jan 29 2025