id:A158692 - OEIS Search Results

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a(n)=33*(33*n^2-1).

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1056, 4323, 9768, 17391, 27192, 39171, 53328, 69663, 88176, 108867, 131736, 156783, 184008, 213411, 244992, 278751, 314688, 352803, 393096, 435567, 480216, 527043, 576048, 627231, 680592, 736131, 793848, 853743, 915816, 980067, 1046496 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`The identity (66n^2-1)^2 - (1089n^2-33) * (2n)^2 = 1 can be written as` `the Pell equation (A158693(n))^2 - a(n) (A005843(n))^2 = 1.`
	LINKS	`Vincenzo Librandi, X^2-AY^2=1` `Edward Everett Withford, Pell Equation` `Wolfram MathWorld, Pell Equation`
	FORMULA	`a(n)= 3a(n-1) -3a(n-2) +a(n-3). G.f.: 33x(-32-35*x+x^2)/(x-1)^3.`
	CROSSREFS	`Cf. A005843, A158693` `Sequence in context: A090057 A020389 A090005 this_sequence A023072 A035858 A120215` `Adjacent sequences: A158689 A158690 A158691 this_sequence A158693 A158694 A158695`
	KEYWORD	`nonn,easy`
	AUTHOR	`Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 24 2009`
	EXTENSIONS	`Comment rewritten and formula replaced by R. J. Mathar, (mathar(AT)strw.leidenuniv.nl), Oct 22 2009`

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Last modified December 13 23:45 EST 2009. Contains 170824 sequences.

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