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A127331
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Primes p such that 6p-7 and 6p+7 are also primes.
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1
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2, 5, 11, 29, 31, 61, 71, 101, 109, 199, 229, 241, 269, 331, 379, 431, 491, 631, 691, 821, 919, 941, 991, 1049, 1061, 1259, 1289, 1321, 1409, 1439, 1451, 1459, 1571, 1621, 1831, 1861, 1931, 2039, 2089, 2161, 2251, 2281, 2311, 2389, 2399, 2441, 2539, 2551
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OFFSET
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1,1
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LINKS
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EXAMPLE
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31, 6*31-7=179, 6*31+7=193 are all primes.
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MATHEMATICA
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Select[Range[5000], PrimeQ[ # ] && PrimeQ[6# + 7] && PrimeQ[6# - 7] &]
Select[Prime[Range[3000]], PrimeQ[6 # - 7] && PrimeQ[6 # + 7]&] (* Vincenzo Librandi, Apr 09 2013 *)
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PROG
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(Magma) [p: p in PrimesUpTo(2600) | IsPrime(6*p-7) and IsPrime(6*p+7)]; // Vincenzo Librandi, Apr 09 2013
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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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STATUS
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approved
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