id:A158771 - OEIS Search Results

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a(n)=78*n^2-1.

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77, 311, 701, 1247, 1949, 2807, 3821, 4991, 6317, 7799, 9437, 11231, 13181, 15287, 17549, 19967, 22541, 25271, 28157, 31199, 34397, 37751, 41261, 44927, 48749, 52727, 56861, 61151, 65597, 70199, 74957, 79871, 84941, 90167, 95549, 101087 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`The identity (78n^2-1)^2 - (1521n^2-39) * (2n)^2 = 1 can be written as` `the Pell equation (a(n))^2 - A158770(n) (A005843(n))^2 = 1.`
	LINKS	`Edward Everett Withford, Pell Equation` `Wolfram MathWorld, Pell Equation` `Vincenzo Librandi, X^2-AY^2=1`
	FORMULA	`a(n)= 3a(n-1) -3a(n-2) +a(n-3). G.f.: x(-77-80x+x^2)/(x-1)^3.`
	CROSSREFS	`Cf. A005843, A158770` `Sequence in context: A029558 A156652 A158767 this_sequence A020206 A020304 A154058` `Adjacent sequences: A158768 A158769 A158770 this_sequence A158772 A158773 A158774`
	KEYWORD	`nonn,easy`
	AUTHOR	`Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 26 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 November 23 17:09 EST 2009. Contains 167438 sequences.

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