id:A158554 - OEIS Search Results

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a(n)=28*n^2-1.

+0
2

27, 111, 251, 447, 699, 1007, 1371, 1791, 2267, 2799, 3387, 4031, 4731, 5487, 6299, 7167, 8091, 9071, 10107, 11199, 12347, 13551, 14811, 16127, 17499, 18927, 20411, 21951, 23547, 25199, 26907, 28671, 30491, 32367, 34299, 36287, 38331, 40431 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`The identity (28n^2-1)^2 - (196n^2-14) * (2n)^2 = 1 can be written` `in Pell-type form as (a(n))^2 - A158553(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.: x(-27-30x+x^2)/(x-1)^3.`
	CROSSREFS	`Cf. A005843, A158553` `Sequence in context: A042424 A143938 A042428 this_sequence A029699 A087795 A036927` `Adjacent sequences: A158551 A158552 A158553 this_sequence A158555 A158556 A158557`
	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 December 15 00:47 EST 2009. Contains 170825 sequences.

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