id:A158559 - OEIS Search Results

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a(n)=15*(15*n^2-1).

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210, 885, 2010, 3585, 5610, 8085, 11010, 14385, 18210, 22485, 27210, 32385, 38010, 44085, 50610, 57585, 65010, 72885, 81210, 89985, 99210, 108885, 119010, 129585, 140610, 152085, 164010, 176385, 189210, 202485, 216210, 230385, 245010, 260085 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`The identity (30n^2-1)^2 - (225n^2-15) * (2n)^2 = 1 can be written` `in Pell-type form as (A158560(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.: 15x(-14-17*x+x^2)/(x-1)^3.`
	CROSSREFS	`Cf. A005843, A158560` `Sequence in context: A118279 A163263 A009127 this_sequence A046302 A157408 A118281` `Adjacent sequences: A158556 A158557 A158558 this_sequence A158560 A158561 A158562`
	KEYWORD	`nonn,easy`
	AUTHOR	`Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 21 2009`
	EXTENSIONS	`Comment rewritten - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 16 2009`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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