A239760 Number of pairs of functions (f,g) from a set of n elements into itself satisfying f(x) = f(f(g(x))).

1, 1, 10, 123, 1984, 38765, 899856, 24135055, 734381824, 24985937241, 939674886400, 38697245287811, 1731506682516480, 83631998873272837, 4336190248653942784, 240186479159794548375, 14153996066789439471616, 884109266328681103701425, 58346867827408911965945856

Offset

0,3

Links

David Einstein, Table of n, a(n) for n = 0..100

David Einstein, Sage notebook for A239760

Crossrefs

Cf. A000248, A000949.

Sequence in context: A246643 A233084 A081784 * A296190 A263552 A259839

Adjacent sequences: A239757 A239758 A239759 * A239761 A239762 A239763

Keyword

nonn

Author

Chad Brewbaker, Mar 26 2014

Extensions

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

More terms from David Einstein, Nov 15 2016

Status

approved