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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. +0
5
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 (list; graph; listen)
OFFSET

1,1

COMMENT

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: A165836 A094836 A004504 this_sequence A138598 A160661 A114841

Adjacent sequences: A090458 A090459 A090460 this_sequence A090462 A090463 A090464

KEYWORD

nonn

AUTHOR

T. D. Noe (noe(AT)sspectra.com), Dec 01 2003

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Last modified December 20 00:58 EST 2009. Contains 171054 sequences.


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