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Search: id:A158640
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| 51, 207, 467, 831, 1299, 1871, 2547, 3327, 4211, 5199, 6291, 7487, 8787, 10191, 11699, 13311, 15027, 16847, 18771, 20799, 22931, 25167, 27507, 29951, 32499, 35151, 37907, 40767, 43731, 46799, 49971, 53247, 56627, 60111, 63699, 67391
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OFFSET
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1,1
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COMMENT
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The identity (52*n^2-1)^2 - (676*n^2-26) * (2*n)^2 = 1 can be written as
the Pell equation (a(n))^2 - A158639(n) * (A005843(n))^2 =1.
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LINKS
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Vincenzo Librandi, X^2-AY^2=1
Edward Everett Withford, Pell Equation
Wolfram MathWorld, Pell Equation
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FORMULA
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a(n)= 3*a(n-1) -3*a(n-2) +a(n-3). G.f.: x*(-51-54*x+x^2)/(x-1)^3.
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CROSSREFS
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Cf. A158639
Sequence in context: A157365 A157916 A007264 this_sequence A107253 A030535 A155464
Adjacent sequences: A158637 A158638 A158639 this_sequence A158641 A158642 A158643
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KEYWORD
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nonn,easy
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AUTHOR
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Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 23 2009
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EXTENSIONS
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Comment rephrased and redundant formula replaced by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 19 2009
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