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Search: id:A157949
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| 127, 255, 383, 511, 639, 767, 895, 1023, 1151, 1279, 1407, 1535, 1663, 1791, 1919, 2047, 2175, 2303, 2431, 2559, 2687, 2815, 2943, 3071, 3199, 3327, 3455, 3583, 3711, 3839, 3967, 4095, 4223, 4351, 4479, 4607, 4735, 4863, 4991, 5119, 5247, 5375, 5503
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OFFSET
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1,1
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COMMENT
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If A=[A157948] 64*n.^2-n (63, 254, 573,.,); Y=[A010855] 16 (16, 16, 16, ,.,); X=[A157949] 128*n-1 1 (127, 255, 383.,), we have, for all terms, Pell's equation X^2-A*Y^2=1. Example: 127^2-63 *16^2=1; 255^2-254*16^2=1; 383^2-573*16^2=1.
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LINKS
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Edward Everett Withford, Pell Equation
Wolfram MathWorld, Pell Equation
Vincenzo Librandi, X^2-AY^2=1
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FORMULA
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a(n)=128*n-1 (n>0)
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EXAMPLE
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For n=1, a(1)=127; n=2, a(2)=255; n=3, a(3)=383
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CROSSREFS
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Cf. A157948, A010855
Sequence in context: A142551 A048453 A138127 this_sequence A142165 A031933 A080035
Adjacent sequences: A157946 A157947 A157948 this_sequence A157950 A157951 A157952
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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 10 2009
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