A239756 Number of pairs of functions (f,g) from a set of n elements into itself satisfying f(f(g(x))) = g(g(x)).
1, 1, 8, 129, 3616, 151845, 8864496, 682005919
Offset: 0
Extensions
a(6)-a(7) from Giovanni Resta, Mar 28 2014
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.