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A152843
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Numbers n such that both 2n+3 and 4n+7 are prime.
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2
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0, 1, 4, 10, 13, 19, 25, 40, 43, 55, 64, 85, 88, 94, 115, 118, 124, 139, 145, 178, 208, 214, 220, 244, 253, 295, 319, 325, 328, 340, 358, 370, 379, 403, 454, 475, 505, 508, 514, 523, 550, 610, 613, 643, 703, 718, 724, 739, 748, 754, 778, 790, 799, 865, 904, 943
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OFFSET
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1,3
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COMMENTS
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Or, numbers n such that 2n+3 is a Sophie Germain prime. [Klaus Brockhaus, Dec 22 2008]
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LINKS
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EXAMPLE
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For n = 10, 2*n+3 = 23 is prime and 4*n+7 = 47 is prime. 23 = A005384(5).
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MATHEMATICA
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Join[{0}, Select[Range[1000], PrimeQ[2*#+3] && PrimeQ[4*#+7] &]] (* Vincenzo Librandi, Aug 30 2012 *)
Select[Range[0, 1000], AllTrue[{2#+3, 4#+7}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Aug 07 2015 *)
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PROG
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(Magma) [ n: n in [0..1000] | IsPrime(2*n+3) and IsPrime(4*n+7) ];
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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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