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Search: id:A158767
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| 1, 77, 305, 685, 1217, 1901, 2737, 3725, 4865, 6157, 7601, 9197, 10945, 12845, 14897, 17101, 19457, 21965, 24625, 27437, 30401, 33517, 36785, 40205, 43777, 47501, 51377, 55405, 59585, 63917, 68401, 73037, 77825, 82765, 87857, 93101, 98497
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OFFSET
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0,2
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COMMENT
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The identity (76*n^2+1)^2 - (1444*n^2+38) * (2*n)^2 = 1 can be written as
the Pell equation (a(n))^2 - A158766(n) * (A005843(n))^2 = 1.
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LINKS
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Wolfram MathWorld, Pell Equation
Edward Everett Withford, Pell Equation
Vincenzo Librandi, X^2-AY^2=1
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FORMULA
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a(n)= 3*a(n-1) -3*a(n-2) +a(n-3). G.f.: -(1+74*x+77*x^2)/(x-1)^3.
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CROSSREFS
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Cf. A005843, A158766
Sequence in context: A044790 A029558 A156652 this_sequence A158771 A020206 A020304
Adjacent sequences: A158764 A158765 A158766 this_sequence A158768 A158769 A158770
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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 26 2009
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EXTENSIONS
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Comment rewritten, a(0) added, and formula replaced by R. J. Mathar, (mathar(AT)strw.leidenuniv.nl), Oct 22 2009
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