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Search: id:A145120
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| A145120 |
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Numbers X such that (X^2-19)/57 is a square |
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+0
2
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| 38, 11438, 3454238, 1043168438, 315033414038, 95139047871038, 28731677423639438, 8676871442891239238, 2620386444075730610438, 791348029239427753113038, 238984484443863105709527038
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OFFSET
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1,1
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FORMULA
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a(n+2)=302*a(n+1)-a(n)
a(n)=19*{[151+20*sqrt(57)]^n+[151-20*sqrt(57)]^n}-(5/2)*sqrt(57)*{[151-20*sqrt(57)]^n-[151+20*sqrt(57)]^n }, with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Nov 25 2008]
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EXAMPLE
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a(1)=38 because 38^2=57*25+19
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CROSSREFS
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Sequence in context: A093648 A055605 A096558 this_sequence A030260 A145122 A134182
Adjacent sequences: A145117 A145118 A145119 this_sequence A145121 A145122 A145123
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KEYWORD
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easy,nonn
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AUTHOR
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Richard Choulet (richardchoulet(AT)yahoo.fr), Oct 02 2008
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