id:A065888 - OEIS Search Results

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a(n) = number of endofunctions on [n] with a 4-cycle a->b->c->d->a, and for any x in [n], some iterate f^k(x) = a.

+0
2

6, 120, 2160, 41160, 860160, 19840464, 504000000, 14030763120, 425681879040, 13997939172360, 496360987938816, 18891066796875000, 768426686420090880, 33279382190563948320, 1529238539734890577920, 74326797938267012471904 (list; graph; listen)

	OFFSET	`4,1`
	FORMULA	`E.g.f.: T^4/4 where T = T(x) is Euler's tree function (see A000169).`
	EXAMPLE	`a(4) = 6 : 3 [choices of 1's opposite in cycle] * 2 [choices of 1's image]`
	CROSSREFS	`Cf. A000169 (1-cycle), A053506 (2-cycle), A065513 (3-cycle), A065889 (= A065888/2: underlying simple graphs).` `Sequence in context: A048604 A001516 A026337 this_sequence A075844 A029697 A126448` `Adjacent sequences: A065885 A065886 A065887 this_sequence A065889 A065890 A065891`
	KEYWORD	`nonn`
	AUTHOR	`Len Smiley (smiley(AT)math.uaa.alaska.edu), Nov 27 2001`

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Last modified July 26 13:41 EDT 2008. Contains 142293 sequences.

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