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Search: id:A104240
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| A104240 |
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Nonnegative integers n such that 13*n^2 + 13*n + 1 is a square. |
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+0
4
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| 0, 0, 7, 144, 504, 9727, 187560, 654840, 12626287, 243453384, 849982464, 16388911447, 316002305520, 1103276584080, 21272794432567, 410170749112224
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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The next terms appear to be 243453384, 849982464, 16388911447.
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FORMULA
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a(1)=0, a(2)=0, a(3)=7, a(4)=144, a(5)=504, a(6)=9727 and then a(n)=1298*a(n-3)+648-a(n-6), 13*(a(n)^2)+13*a(n)+1 = a square. - Pierre CAMI (pierrecami(AT)tele2.fr), Apr 05 2005
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PROGRAM
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(PARI) for(n=0, 12626287, if(issquare(13*n*(n+1)+1), print1(n, ", ")))
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CROSSREFS
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Sequence in context: A070074 A051397 A082157 this_sequence A156978 A163028 A012826
Adjacent sequences: A104237 A104238 A104239 this_sequence A104241 A104242 A104243
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KEYWORD
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nonn
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AUTHOR
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Gerald McGarvey (Gerald.McGarvey(AT)comcast.net), Apr 02 2005
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EXTENSIONS
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More terms from Pierre CAMI (pierrecami(AT)tele2.fr), Apr 05 2005
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