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Search: id:A161864
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| A161864 |
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Numbers n such that n^2+n+5 and n^2+n-5 are both prime. |
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+0
2
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| 3, 6, 11, 18, 21, 23, 27, 32, 42, 48, 51, 83, 86, 93, 116, 153, 158, 182, 188, 216, 282, 291, 317, 333, 396, 482, 681, 737, 786, 798, 818, 821, 872, 923, 956, 966, 977, 986, 1007, 1026, 1077, 1082, 1106, 1161, 1287, 1292, 1302, 1337, 1341, 1451, 1467, 1563
(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+-5 are primes. a(2)=6 as 42+-5 are primes.
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MATHEMATICA
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q=5; lst5={}; Do[p=n^2+n; If[PrimeQ[p-q]&&PrimeQ[p+q], AppendTo[lst5, n]], {n, 0, 7!}]; lst5
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CROSSREFS
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Cf. A088485, A161863
Sequence in context: A109471 A124454 A013932 this_sequence A010335 A084576 A024667
Adjacent sequences: A161861 A161862 A161863 this_sequence A161865 A161866 A161867
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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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