id:A091626 - OEIS Search Results

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Number of ordered integer pairs (b,c) with 0 <=b, c <= n such that both roots of x^2+bx+c=0 are integers.

+0
3

1, 2, 4, 6, 9, 11, 14, 16, 19, 22, 25, 27, 31, 33, 36, 39, 43, 45, 49, 51, 55, 58, 61, 63, 68, 71, 74, 77, 81, 83, 88, 90, 94, 97, 100, 103, 109, 111, 114, 117, 122, 124, 129, 131, 135, 139, 142, 144, 150, 153, 157, 160, 164, 166, 171, 174, 179, 182, 185, 187 (list; graph; listen)

	OFFSET	`0,2`
	LINKS	`Eric Weisstein's World of Mathematics, Quadratic Equation`
	FORMULA	`a(n)=a(n-1)+ceil(tau(n)/2)+1, n>1. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Jun 12 2004`
	CROSSREFS	`Cf. A067274, A091627.` `Cf. A038548.` `Sequence in context: A059545 A061785 A047292 this_sequence A085223 A138326 A050502` `Adjacent sequences: A091623 A091624 A091625 this_sequence A091627 A091628 A091629`
	KEYWORD	`nonn`
	AUTHOR	`Eric Weisstein (eric(AT)weisstein.com), Jan 24, 2004`

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Last modified September 6 16:04 EDT 2008. Contains 143483 sequences.

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