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 A239778 #16 Oct 24 2024 14:37:38 %S A239778 1,1,12,255,8968,452485,31456656,2899786855,343386848064 %N A239778 Number of pairs of functions f, g from a size n set into itself satisfying f(f(f(x))) = f(g(g(x))). %H A239778 Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/A239778.c">C program</a>. %H A239778 Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/A239778.py">Python program</a>. %p A239778 s:= proc(n, i) option remember; `if`(i=0, [[]], %p A239778 map(x-> seq([j, x[]], j=1..n), s(n, i-1))) %p A239778 end: %p A239778 a:= proc(n) (l-> add(add(`if`([true$n]=[seq(evalb( %p A239778 f[f[f[i]]]=f[g[g[i]]]), i=1..n)], 1, 0), g=l), f=l))(s(n$2)) %p A239778 end: %p A239778 seq(a(n), n=0..5); # _Alois P. Heinz_, Jul 16 2014 %Y A239778 Cf. A181162, A239769, A239773. %K A239778 nonn,more,hard %O A239778 0,3 %A A239778 _Chad Brewbaker_, Mar 26 2014 %E A239778 a(6)-a(7) from _Giovanni Resta_, Mar 28 2014 %E A239778 a(8) from _Lucas A. Brown_, Oct 23 2024