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A024892
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Numbers n such that 3*n+1 is prime.
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9
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2, 4, 6, 10, 12, 14, 20, 22, 24, 26, 32, 34, 36, 42, 46, 50, 52, 54, 60, 64, 66, 70, 74, 76, 80, 90, 92, 94, 102, 104, 110, 112, 116, 122, 124, 126, 132, 136, 140, 144, 146, 152, 154, 162, 166, 174, 180, 182, 190, 192, 200, 202, 204, 206, 210, 214, 220, 224, 230, 236, 242, 244, 246
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OFFSET
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1,1
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COMMENTS
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All the primes (with the exception of 3), can be expressed as 3*n+1 or 3*n-1. - César Aguilera, Apr 13 2013
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..1000
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FORMULA
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a(n) = 2*A024899(n) = A034936(n)+1
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MATHEMATICA
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lst={}; Do[p=3*n+1; If[PrimeQ[p], AppendTo[lst, n]], {n, 0, 10^3}]; lst (* Vladimir Joseph Stephan Orlovsky, Sep 10 2008 *)
Select[Range[250], PrimeQ[3# + 1] &] (* Vincenzo Librandi, Sep 25 2012 *)
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PROG
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(MAGMA) [n: n in [1..1000] | IsPrime(3*n+1)]; // Vincenzo Librandi, Nov 20 2010
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CROSSREFS
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Cf. A002476 (associated primes), A091178 (gives prime index).
Sequence in context: A141104 A047410 A164875 * A087136 A015921 A132631
Adjacent sequences: A024889 A024890 A024891 * A024893 A024894 A024895
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KEYWORD
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nonn,easy
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AUTHOR
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Clark Kimberling
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STATUS
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approved
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