id:A158549 - OEIS Search Results

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a(n)=26*n^2+1.

+0
2

1, 27, 105, 235, 417, 651, 937, 1275, 1665, 2107, 2601, 3147, 3745, 4395, 5097, 5851, 6657, 7515, 8425, 9387, 10401, 11467, 12585, 13755, 14977, 16251, 17577, 18955, 20385, 21867, 23401, 24987, 26625, 28315, 30057, 31851, 33697, 35595, 37545 (list; graph; listen)

	OFFSET	`0,2`
	COMMENT	`The identity (26n^2+1)^2 - (169n^2+13) * (2n)^2 = 1 can be written as` `(a(n))^2 - A158548(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.: (1+24x+27x^2)/(1-x)^3.`
	CROSSREFS	`Cf. A005843, A158548` `Sequence in context: A036346 A140376 A046347 this_sequence A044278 A044659 A134171` `Adjacent sequences: A158546 A158547 A158548 this_sequence A158550 A158551 A158552`
	KEYWORD	`nonn,easy`
	AUTHOR	`Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 21 2009`
	EXTENSIONS	`Comment rewritten, a(0) added - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 16 2009`

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Last modified December 17 13:29 EST 2009. Contains 170826 sequences.

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