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Search: id:A028870
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| A028870 |
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Numbers n such that n^2 - 2 is prime. |
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19
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| 2, 3, 5, 7, 9, 13, 15, 19, 21, 27, 29, 33, 35, 37, 43, 47, 49, 55, 61, 63, 69, 71, 75, 77, 89, 93, 103, 107, 117, 119, 121, 127, 131, 135, 139, 145, 155, 161, 169, 173, 177, 183, 191, 205, 211, 217, 223, 231, 233, 237, 239, 247, 253, 257, 259, 265, 267
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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It is conjectured that this sequence is infinite.
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REFERENCES
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D. Shanks, Solved and Unsolved Problems in Number Theory, 2nd. ed., Chelsea, 1978, p. 31.
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LINKS
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P. De Geest, Palindromic Quasipronics of the form n(n+x)
Eric Weisstein's World of Mathematics, Near-Square Prime
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MATHEMATICA
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a[n_]:=n^x-y; lst={}; x=2; y=2; Do[If[PrimeQ[a[n]], AppendTo[lst, n]], {n, 0, 6!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Jan 03 2009]
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CROSSREFS
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Cf. A028871.
Adjacent sequences: A028867 A028868 A028869 this_sequence A028871 A028872 A028873
Sequence in context: A102424 A080000 A032459 this_sequence A057886 A069999 A035563
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KEYWORD
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nonn
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AUTHOR
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Patrick De Geest (pdg(AT)worldofnumbers.com)
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