A239754 Number of pairs of functions (f,g) from a set of n elements into itself satisfying f(g(f(x))) = g(g(g(x))).

1, 1, 8, 111, 2896, 119985, 7180776, 581563129

Offset

0,3

Links

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

Crossrefs

Cf. A000248, A000949.

Sequence in context: A079660 A131621 A364983 * A003721 A281951 A316179

Adjacent sequences: A239751 A239752 A239753 * A239755 A239756 A239757

Keyword

nonn,more

Author

Chad Brewbaker, Mar 26 2014

Extensions

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

Status

approved