A239785 Number of pairs of functions (f,g) from a set of n elements into itself satisfying f(g(g(x))) = f(g(x)).

1, 1, 14, 411, 19912, 1412745, 136537056, 17121680443

Offset

0,3

Links

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

Crossrefs

Cf. A181162.

Sequence in context: A041364 A353609 A222904 * A275025 A236156 A258392

Adjacent sequences: A239782 A239783 A239784 * A239786 A239787 A239788

Keyword

nonn,more

Author

Chad Brewbaker, Mar 26 2014

Extensions

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

Status

approved