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A045753
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Numbers n such that 4n-1 and 4n+1 are both primes.
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14
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1, 3, 15, 18, 27, 45, 48, 57, 60, 78, 87, 105, 108, 150, 165, 207, 255, 258, 273, 288, 330, 357, 363, 372, 402, 405, 417, 447, 468, 483, 507, 522, 528, 567, 585, 648, 672, 678, 750, 780, 792, 813, 825, 840, 843, 867, 882, 885, 918, 942, 963, 1005, 1023
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OFFSET
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1,2
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LINKS
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EXAMPLE
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3 belongs to the sequence because 4*3+1 and 4*3-1 are both primes.
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MATHEMATICA
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Select[Range[1023], And @@ PrimeQ[{-1, 1} + 4# ] &] (* Ray Chandler, Dec 06 2006 *)
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PROG
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(Magma) [n: n in [1..2000] | IsPrime(4*n+1) and IsPrime(4*n-1)] // Vincenzo Librandi, Nov 18 2010
(PARI) list(lim)=my(v=List(), p=2); forprime(q=3, 4*lim+1, if(q-p==2 && p%4==3, listput(v, q\4)); p=q); Vec(v) \\ Charles R Greathouse IV, Dec 03 2016
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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