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Search: id:A158733
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| 35, 1260, 4935, 11060, 19635, 30660, 44135, 60060, 78435, 99260, 122535, 148260, 176435, 207060, 240135, 275660, 313635, 354060, 396935, 442260, 490035, 540260, 592935, 648060, 705635, 765660, 828135, 893060, 960435, 1030260, 1102535
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OFFSET
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0,1
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COMMENT
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The identity (70*n^2+1)^2 - (1225*n^2+35) * (2*n)^2 = 1 can be written as
the Pell equation (A158734(n))^2 - a(n) * (A005843(n))^2 = 1.
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LINKS
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Wolfram MathWorld, Pell Equation
Vincenzo Librandi, X^2-AY^2=1
Edward Everett Withford, 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.: -35*(1+33*x+36*x^2)/(x-1)^3.
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CROSSREFS
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Cf. A005843, A158734
Sequence in context: A126158 A095153 A009979 this_sequence A029560 A135923 A130005
Adjacent sequences: A158730 A158731 A158732 this_sequence A158734 A158735 A158736
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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 25 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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