A102687 - OEIS

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A102687

Number of different squares of mappings of a finite set of n elements into itself.

1, 3, 12, 100, 1075, 13356, 197764, 3403576, 66159405 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,2`
	COMMENTS	`Let A be a finite set of cardinal n, F be the set of mappings from A to A and F_2 be the subset of F including all g such that there exists f in F with g = fof (composition of f with itself). Then a(n) = #F_2.`
	LINKS	`Table of n, a(n) for n=1..9.`
	CROSSREFS	`Cf. A102709.` `Sequence in context: A162055 A067300 A133359 * A202302 A141535 A111485` `Adjacent sequences: A102684 A102685 A102686 * A102688 A102689 A102690`
	KEYWORD	`nonn,more,changed`
	AUTHOR	`Eric Wegrzynowski (Eric.Wegrzynowski(AT)lifl.fr), Feb 03 2005`
	EXTENSIONS	`a(7) from Vladeta Jovovic, Feb 05 2005` `a(8) and a(9) from Joshua Zucker, May 18 2006`
	STATUS	`approved`

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Last modified May 22 01:31 EDT 2013. Contains 225509 sequences.