A239762 Number of pairs of functions (f,g) from a set of n elements into itself satisfying f(f(g(x))) = g(f(x)).

1, 1, 10, 159, 3568, 106545, 4062336, 192754009

Offset

0,3

Links

Table of n, a(n) for n=0..7.

Crossrefs

Cf. A181162.

Sequence in context: A239761 A245916 A245914 * A087961 A360935 A116041

Adjacent sequences: A239759 A239760 A239761 * A239763 A239764 A239765

Keyword

nonn,more

Author

Chad Brewbaker, Mar 26 2014

Extensions

a(6)-a(7) from Giovanni Resta, Mar 28 2014

Status

approved