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Search: id:A157436
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| A157436 |
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a(n)=128*n^2+528*n+12481 (n>0) |
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+0
3
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| 15137, 18049, 21217, 24641, 28321, 32257, 36449, 40897, 45601, 50561, 55777, 61249, 66977, 72961, 79201, 85697, 92449, 99457, 106721, 114241, 122017, 130049, 138337, 146881, 155681, 164737, 174049, 183617, 193441, 203521, 213857, 224449
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OFFSET
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1,1
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COMMENT
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If A=[A157434] 4*n.^2+79*n +390 (473,564,663,770,.,); Y=[A157435] 64*n+632 (696, 760, 824,888,..,); X=[A157433] 128*n^2+2528*n+12481 (15137,18049,21217,24641,.,) ; , we have for all terms, Pell's equation X^2-A*Y^2=1. Example: 15137^2-473*696^2=1; 18049^2-564*760^2=1; 21217^2-663*824^2=1.
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LINKS
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Vincenzo Librandi, X^2-AY^2=1
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FORMULA
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a(n)=128*n^2+528*n+12481 (n>0)
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EXAMPLE
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For n=1, a(1)=15137; n=2, a(2)=18049; n=3, a(3)=21217
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CROSSREFS
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Cf. A157434, A157435
Sequence in context: A004935 A004955 A004975 this_sequence A105924 A115924 A064982
Adjacent sequences: A157433 A157434 A157435 this_sequence A157437 A157438 A157439
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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 01 2009
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