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 A239839 #16 Mar 12 2015 12:17:31 %S A239839 1,1,4,18,168,1560,20880,267120,5080320,93623040,2184537600, %T A239839 49896000000,1451853849600,41739720422400,1426847092070400, %U A239839 47989033956864000,1919268439216128000,76229151152394240000,3471527082588364800000,156226856133456396288000 %N A239839 Number of ordered pairs of permutation functions on n elements satisfying f(f(f(x))) = g(f(g(x))). %H A239839 Hiroaki Yamanouchi, <a href="/A239839/b239839.txt">Table of n, a(n) for n = 0..60</a> %Y A239839 Cf. A000012, A000085, A000142, A088311, A053529, A001044. %K A239839 nonn %O A239839 0,3 %A A239839 _Chad Brewbaker_, Mar 27 2014 %E A239839 a(8)-a(9) from _Giovanni Resta_, Mar 27 2014 %E A239839 a(10)-a(13) from _Paul Boddington_, Feb 23 2015 %E A239839 a(14)-a(19) from _Hiroaki Yamanouchi_, Mar 12 2015