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Search: id:A075871
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| A075871 |
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Numbers n such that 13*n^2 + 1 is a square. |
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+0
1
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| 0, 180, 233640, 303264540, 393637139280, 510940703520900, 663200639532988920, 860833919173116097260, 1117361763886065161254560, 1450334708690193406192321620, 1882533334518107155172472208200
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OFFSET
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1,2
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COMMENT
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Lim_{n-> Inf.} a(n)/a(n-1) = 649 + 180*Sqrt(13).
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LINKS
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Tanya Khovanova, Recursive Sequences
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FORMULA
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a(n)=1298*a(n-1)-a(n-2), n>1. - Michael Somos, Oct 30 2002
a(n) = [(649+180*Sqrt(13))^n - (649-180*Sqrt(13))^n] / (2*Sqrt(13))
a(n) = 1297*(a(n-1)+a(n-2))-a(n-3). a(n) = 1299*(a(n-1)-a(n-2))+a(n-3). - Mohamed Bouhamida (bhmd95(AT)yahoo.fr), Sep 20 2006
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CROSSREFS
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Sequence in context: A035830 A091033 A057867 this_sequence A074811 A036200 A139649
Adjacent sequences: A075868 A075869 A075870 this_sequence A075872 A075873 A075874
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KEYWORD
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nonn
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AUTHOR
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Gregory V. Richardson (omomom(AT)hotmail.com), Oct 16 2002
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