A239756 - OEIS

A239756

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

1, 1, 8, 129, 3616, 151845, 8864496, 682005919 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`0,3`
	LINKS	`Table of n, a(n) for n=0..7.`
	CROSSREFS	`Cf. A000248, A000949.` `Sequence in context: A348207 A338328 A073701 * A295240 A240630 A187609` `Adjacent sequences: A239753 A239754 A239755 * A239757 A239758 A239759`
	KEYWORD	`nonn,more`
	AUTHOR	`Chad Brewbaker, Mar 26 2014`
	EXTENSIONS	`a(6)-a(7) from Giovanni Resta, Mar 28 2014`
	STATUS	`approved`

Last modified May 25 22:51 EDT 2022. Contains 354073 sequences. (Running on oeis4.)