A239758 Number of pairs of functions (f,g) on a set of n elements into itself satisfying f(g(f(x))) = g(f(g(x))).

1, 1, 8, 147, 4672, 221245, 14695656, 1297497103

Offset

0,3

Links

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

Crossrefs

Cf. A000248, A000949.

Sequence in context: A064331 A230938 A351922 * A239759 A279127 A259991

Adjacent sequences: A239755 A239756 A239757 * A239759 A239760 A239761

Keyword

nonn,more

Author

Chad Brewbaker, Mar 26 2014

Extensions

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

Status

approved