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A007591
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Numbers n such that n^2+4 is prime.
(Formerly M2416)
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15
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1, 3, 5, 7, 13, 15, 17, 27, 33, 35, 37, 45, 47, 57, 65, 67, 73, 85, 87, 95, 97, 103, 115, 117, 125, 135, 137, 147, 155, 163, 167, 177, 183, 193, 203, 207, 215, 217, 233, 235, 243, 245, 253, 255, 265, 267, 275, 277, 287, 293, 303, 307, 313, 317, 347, 357, 373, 375
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OFFSET
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1,2
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Near-Square Prime
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MATHEMATICA
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lst={}; Do[If[PrimeQ[n^2+4], Print[n]; AppendTo[lst, n]], {n, 10^5}]; lst [From Vladimir Joseph Stephan Orlovsky, Aug 21 2008]
Select[Range[0, 400], PrimeQ[#^2 + 4] &] (* Vincenzo Librandi, Sep 25 2012 *)
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PROG
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(MAGMA) [n: n in [0..400] | IsPrime(n^2+4)]; [From Vincenzo Librandi, Nov 18 2010]
(PARI) select(n->isprime(n^4+4), vector(500, n, 2*n-1)) \\ Charles R Greathouse IV, Sep 25 2012
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CROSSREFS
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Sequence in context: A092793 A024909 A063241 * A097687 A032911 A157834
Adjacent sequences: A007588 A007589 A007590 * A007592 A007593 A007594
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane, R. K. Guy.
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STATUS
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approved
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