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Search: id:A157510
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| 1020, 2020, 3020, 4020, 5020, 6020, 7020, 8020, 9020, 10020, 11020, 12020, 13020, 14020, 15020, 16020, 17020, 18020, 19020, 20020, 21020, 22020, 23020, 24020, 25020, 26020, 27020, 28020, 29020, 30020, 31020, 32020, 33020, 34020, 35020
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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If A=[A031434] 25*n.^2+n (26,102,228,.,); Y=[A157510] 1000*n+20 (1020,2020,3020..,); X=[A157511] 5000*n^2+200*n+1 (5201,20401,45601,.,), we have, for all terms, Pell's equation X^2-A*Y^2=1. Example: 5201^2-26*1020^2=1; 20401^2-102*2020^2=1; 45601^2-228*3020^2=1.
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LINKS
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Wolfram MathWorld, Pell Equation
Vincenzo Librandi, X^2-AY^2=1
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FORMULA
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a(n)=1000*n+20 (n>0)
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EXAMPLE
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For n=1, a(1)=1020; n=2, a(2)=2020; n=3, a(3)=3020
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CROSSREFS
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Cf. A031434, A157511
Sequence in context: A087837 A051982 A104444 this_sequence A015160 A102925 A024020
Adjacent sequences: A157507 A157508 A157509 this_sequence A157511 A157512 A157513
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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 02 2009
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