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A157834
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Numbers n such that 3n-2 and 3n+2 are both prime.
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6
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3, 5, 7, 13, 15, 23, 27, 33, 35, 37, 43, 55, 65, 75, 77, 93, 103, 105, 117, 127, 133, 147, 153, 155, 163, 167, 205, 215, 225, 247, 253, 257, 275, 285, 287, 293, 295, 303, 313, 323, 337, 363, 365, 405, 427, 433, 435, 475, 477, 483, 495, 497, 517
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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EXAMPLE
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15*3 +/- 2 = 43,47 (both prime).
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MAPLE
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select(t -> isprime(3*t+2) and isprime(3*t-2), [seq(t, t=3..1000, 2)]); # Robert Israel, May 28 2017
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MATHEMATICA
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Select[Range[600], AllTrue[3#+{2, -2}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Feb 03 2019 *)
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PROG
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(Magma) [n: n in [1..1000]|IsPrime(3*n-2)and IsPrime(3*n+2)] // Vincenzo Librandi, Dec 13 2010
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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