A090461 - OEIS

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A090461

Numbers n such that there is a permutation of the numbers 1 to n such that the sum of adjacent numbers is a square.

15, 16, 17, 23, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	COMMENTS	`Conjecture that there is a solution for all n > 24. See A090460 for a count of the number of essentially different solutions.`
	EXAMPLE	`See A071983`
	CROSSREFS	`Cf. A071983, A071984 (number of circular solutions), A090460.` `Cf. A078107 (n for which there is no solution).` `Sequence in context: A094836 A004504 A176294 * A138598 A160661 A114841` `Adjacent sequences: A090458 A090459 A090460 * A090462 A090463 A090464`
	KEYWORD	`nonn`
	AUTHOR	`T. D. Noe (noe(AT)sspectra.com), Dec 01 2003`
	EXTENSIONS	`a(31)-a(69) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Sep 14 2010`

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Last modified February 17 11:46 EST 2012. Contains 206011 sequences.