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A239839 Number of ordered pairs of permutation functions on n elements satisfying f(f(f(x))) = g(f(g(x))). 2
1, 1, 4, 18, 168, 1560, 20880, 267120, 5080320, 93623040, 2184537600, 49896000000, 1451853849600, 41739720422400, 1426847092070400, 47989033956864000, 1919268439216128000, 76229151152394240000, 3471527082588364800000, 156226856133456396288000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Hiroaki Yamanouchi, Table of n, a(n) for n = 0..60

CROSSREFS

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

Sequence in context: A222766 A302827 A007153 * A156870 A240317 A145075

Adjacent sequences:  A239836 A239837 A239838 * A239840 A239841 A239842

KEYWORD

nonn

AUTHOR

Chad Brewbaker, Mar 27 2014

EXTENSIONS

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

a(10)-a(13) from Paul Boddington, Feb 23 2015

a(14)-a(19) from Hiroaki Yamanouchi, Mar 12 2015

STATUS

approved

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Last modified November 13 23:48 EST 2019. Contains 329106 sequences. (Running on oeis4.)