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 A239774 #8 Jul 16 2014 19:00:28 %S A239774 1,1,10,285,14176,1034145,105764256,14367333421 %N A239774 Number of pairs of functions f, g from a size n set into itself satisfying f(f(g(x))) = f(f(f(x))). %p A239774 s:= proc(n, i) option remember; `if`(i=0, [[]], %p A239774 map(x-> seq([j, x[]], j=1..n), s(n, i-1))) %p A239774 end: %p A239774 a:= proc(n) local l; l:= s(n$2); %p A239774 add(add(`if`([seq(evalb(f[f[g[i]]]=f[f[f[i]]]), %p A239774 i=1..n)]=[true$n], 1, 0), g=l), f=l) %p A239774 end: %p A239774 seq(a(n), n=0..5); # _Alois P. Heinz_, Jul 16 2014 %Y A239774 Cf. A181162, A239769, A239773. %K A239774 nonn,more %O A239774 0,3 %A A239774 _Chad Brewbaker_, Mar 26 2014 %E A239774 a(6)-a(7) from _Giovanni Resta_, Mar 28 2014