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Search: id:A158487
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| 56, 248, 568, 1016, 1592, 2296, 3128, 4088, 5176, 6392, 7736, 9208, 10808, 12536, 14392, 16376, 18488, 20728, 23096, 25592, 28216, 30968, 33848, 36856, 39992, 43256, 46648, 50168, 53816, 57592, 61496, 65528, 69688, 73976, 78392, 82936
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OFFSET
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1,1
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COMMENT
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If A=[A158487] 64*n.^2-8 (n>0, 56, 248, 568,.,); Y=[A005843] 2*n (n>0, 2, 4, 6,.,); X = [A141759] 16*n^2-1 (n>0, 15, 63, 143, .,), we have, for all terms, Pell's equation X^2-A*Y^2=1. Example: 15^2-56*2^2=1; 63^2-248*4^2=1; 143^2-568*6^2=1.
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LINKS
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Edward Everett Withford, Pell Equation
Vincenzo Librandi, X^2-AY^2=1
Wolfram MathWorld, Pell Equation
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FORMULA
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a(n)=64*n^2-8 (n>0)
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EXAMPLE
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For n=1, a(1)=56; n=2, a(2)=248; n=3, a(3)=568
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CROSSREFS
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Cf. A005843, A141759
Sequence in context: A115620 A136547 A158481 this_sequence A110554 A005912 A104677
Adjacent sequences: A158484 A158485 A158486 this_sequence A158488 A158489 A158490
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KEYWORD
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nonn
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AUTHOR
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Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 20 2009
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