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Search: id:A157858
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| A157858 |
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a(n)=1728000*n-240 (n>0) |
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+0
3
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| 1727760, 3455760, 5183760, 6911760, 8639760, 10367760, 12095760, 13823760, 15551760, 17279760, 19007760, 20735760, 22463760, 24191760, 25919760, 27647760, 29375760, 31103760, 32831760, 34559760, 36287760, 38015760
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OFFSET
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1,1
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COMMENT
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If A=[A157857] 3600*n.^2-n (3599, 14398, 32397,.,); Y=[A157858] 1728000*n -240 (1727760, 3455760..,); X=[A157859] 103680000*n^2-28800*n +1 (103651201, 414662401,.,), we have, for all terms, Pell's equation X^2-A*Y^2=1. Example: 103651201^2-3599 *1727760^2=1; 414662401^2-14398*3455760^2=1.
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LINKS
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Vincenzo Librandi, X^2-AY^2=1
Edward Everett Withford, Pell Equation
Philippe Chevanne, Pell Equation
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FORMULA
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a(n)=1728000*n-240 (n>0)
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EXAMPLE
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For n=1, a(1)=1727760; n=2, a(2)=3455760; n=3, a(3)=5183760
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CROSSREFS
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Cf. A157857, A157859
Sequence in context: A121887 A151639 A083646 this_sequence A157862 A131639 A124068
Adjacent sequences: A157855 A157856 A157857 this_sequence A157859 A157860 A157861
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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 08 2009
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