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Search: id:A161866
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| A161866 |
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Numbers n such that n^2+n+7 and n^2+n-7 are both prime. |
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+0
1
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| 3, 5, 9, 12, 24, 29, 32, 39, 44, 50, 57, 59, 65, 102, 135, 137, 144, 170, 180, 207, 260, 267, 297, 302, 305, 344, 347, 360, 365, 369, 389, 404, 429, 464, 474, 495, 540, 555, 570, 612, 620, 659, 662, 689, 767, 774, 792, 824, 837, 872, 885, 900, 950, 954, 989
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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a(1)=3 as 12+-7 are primes. a(2)=5 as 30+-7 are primes.
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MATHEMATICA
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q=7; lst7={}; Do[p=n^2+n; If[PrimeQ[p-q]&&PrimeQ[p+q], AppendTo[lst7, n]], {n, 0, 7!}]; lst7
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CROSSREFS
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Cf. A088485, A161863, A161864, A153417.
Sequence in context: A058599 A059093 A084593 this_sequence A102968 A089593 A086748
Adjacent sequences: A161863 A161864 A161865 this_sequence A161867 A161868 A161869
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KEYWORD
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nonn,easy
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AUTHOR
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Vladimir Orlovsky (4vladimir(AT)gmail.com), Jun 20 2009
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EXTENSIONS
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Definition rephrased by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 23 2009
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