id:A117542 - OEIS Search Results

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Number of permutations P of 1..n such that in P and in the inverse of P, every pair of adjacent numbers, and the first and last number, are relatively prime.

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2

1, 2, 6, 8, 36, 16, 127, 320, 581, 1564, 13565, 13760, 149186, 773727, 540538 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Sequence suggested by Leroy Quet (qq-quet(AT)mindspring.com) on the SeqFan mailing list.`
	EXAMPLE	`a(4)=8, since the 8 permutations (1,2,3,4), (1,4,3,2), (2,1,4,3), (2,3,4,1), (4,1,2,3), (3,2,1,4), (3,4,1,2), (4,3,2,1) satisfy the property.`
	CROSSREFS	`Cf. A076220, A117541.` `Sequence in context: A019199 A094678 A076507 this_sequence A045653 A095239 A065953` `Adjacent sequences: A117539 A117540 A117541 this_sequence A117543 A117544 A117545`
	KEYWORD	`nonn`
	AUTHOR	`Giovanni Resta (g.resta(AT)iit.cnr.it), Mar 28 2006`

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Last modified November 18 20:14 EST 2008. Contains 147244 sequences.

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