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A023258
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Primes that remain prime through 2 iterations of function f(x) = 6x + 7.
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2
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5, 17, 29, 37, 89, 127, 199, 229, 269, 347, 359, 379, 397, 499, 769, 809, 929, 947, 977, 1049, 1087, 1129, 1277, 1279, 1367, 1409, 1439, 1489, 1499, 1607, 1609, 1787, 2017, 2039, 2089, 2399, 2539, 2707, 2819, 2837, 2957, 3089, 3109, 3217, 3229, 3389, 3499
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OFFSET
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1,1
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COMMENTS
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Primes p such that 6*p+7 and 36*p+49 are also primes. - Vincenzo Librandi, Aug 04 2010
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LINKS
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FORMULA
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a(n) = 7 or 9 (mod 10) for n > 1. - John Cerkan, Sep 14 2016
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MATHEMATICA
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nrpQ[n_]:=AllTrue[Rest[NestList[6#+7&, n, 2]], PrimeQ]; Select[Prime[ Range[ 500]], nrpQ] (* Harvey P. Dale, Oct 12 2020 *)
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PROG
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(Magma) [n: n in [1..100000] | IsPrime(n) and IsPrime(6*n+7) and IsPrime(36*n+49)] // Vincenzo Librandi, Aug 04 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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