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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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3
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0, 0, 7, 144, 504, 9727, 187560, 654840, 12626287, 243453384, 849982464, 16388911447, 316002305520, 1103276584080, 21272794432567, 410170749112224
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| The next terms appear to be 243453384, 849982464, 16388911447.
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FORMULA
| 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 (pierre-cami(AT)bbox.fr), Apr 05 2005
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PROG
| (PARI) for(n=0, 12626287, if(issquare(13*n*(n+1)+1), print1(n, ", ")))
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CROSSREFS
| Sequence in context: A051397 A179569 A082157 * A156978 A163028 A012826
Adjacent sequences: A104237 A104238 A104239 * A104241 A104242 A104243
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KEYWORD
| nonn
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AUTHOR
| Gerald McGarvey (Gerald.McGarvey(AT)comcast.net), Apr 02 2005
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EXTENSIONS
| More terms from Pierre CAMI (pierre-cami(AT)bbox.fr), Apr 05 2005
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