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A239756 Number of pairs of functions (f,g) from a set of n elements into itself satisfying f(f(g(x))) = g(g(x)). 0
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

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