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A239836 Number of ordered pairs of permutation functions f,g on a size n set where f(g(g(x))) = g(f(f(x))). 5
1, 1, 2, 6, 48, 360, 2880, 20160, 241920, 3265920 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..9.

CROSSREFS

Cf. A000012, A000085, A000142, A088311, A053529, A001044.

Sequence in context: A092143 A281027 A271961 * A052593 A052586 A052554

Adjacent sequences:  A239833 A239834 A239835 * A239837 A239838 A239839

KEYWORD

nonn,more

AUTHOR

Chad Brewbaker, Mar 27 2014

EXTENSIONS

a(8)-a(9) from Giovanni Resta, Mar 27 2014

STATUS

approved

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Last modified February 20 20:34 EST 2020. Contains 332084 sequences. (Running on oeis4.)