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Search: id:A157511
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| A157511 |
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a(n)=5000*n^2+200*n+1 (n>0) |
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+0
3
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| 5201, 20401, 45601, 80801, 126001, 181201, 246401, 321601, 406801, 502001, 607201, 722401, 847601, 982801, 1128001, 1283201, 1448401, 1623601, 1808801, 2004001, 2209201, 2424401, 2649601, 2884801, 3130001, 3385201, 3650401
(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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Vincenzo Librandi, X^2-AY^2=1
Wolfram MathWorld, Pell Equation
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EXAMPLE
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a(n)=5000*n^2+200*n+1 (n>0)
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MAPLE
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For n=1, a(1)=5201; n=2, a(2)=20401; n=3, a(3)=45601
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CROSSREFS
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Cf. A031434, A157510
Sequence in context: A066167 A028549 A093071 this_sequence A165599 A109159 A067224
Adjacent sequences: A157508 A157509 A157510 this_sequence A157512 A157513 A157514
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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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