id:A084216 - OEIS Search Results

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a(n) = smallest integer d such that a quadratic representation (2n+1)= x^2+ d*y^2 exists (x,y positive integers).

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2, 1, 3, 2, 2, 1, 11, 1, 2, 3, 7, 1, 2, 1, 3, 2, 19, 1, 3, 1, 2, 5, 11, 3, 2, 1, 6, 2, 2, 1, 3, 1, 2, 5, 7, 1, 11, 7, 3, 2, 2, 1, 23, 1, 3, 3, 14, 1, 2, 1, 3, 5, 2, 1, 3, 1, 11, 3, 19, 2, 2, 1, 3, 2, 2, 3, 14, 1, 2, 5, 43, 1, 3, 1, 3, 2, 11, 1, 38, 5, 2, 11, 23, 1, 2, 1, 6, 2, 2, 1, 3, 1, 2, 3, 7, 1, 74, 1 (list; graph; listen)

	OFFSET	`1,1`
	EXAMPLE	`a(7)=11 because d=11 is the smallest d giving integer solutions x=2,y=1 in` `(27+1)= x^2+dy^2 = 2^2 + 11* 1^2 = 15.`
	MATHEMATICA	<< NumberTheory`NumberTheoryFunctions`; Table[First@Select[Range[100], !MatchQ[t=QuadraticRepresentation[ #, 2n+1], _QuadraticRepresentation]&, 1], {n, 1, 128}]
	CROSSREFS	`Adjacent sequences: A084213 A084214 A084215 this_sequence A084217 A084218 A084219` `Sequence in context: A080801 A124758 A071481 this_sequence A057514 A033559 A103151`
	KEYWORD	`nonn`
	AUTHOR	`Wouter Meeussen (wouter.meeussen(AT)pandora.be), Jun 20 2003`

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Last modified May 16 01:24 EDT 2008. Contains 139630 sequences.

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