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A023248
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Primes that remain prime through 2 iterations of function f(x) = 3x + 8.
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4
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3, 11, 13, 31, 41, 43, 53, 101, 113, 211, 223, 263, 283, 431, 433, 491, 521, 563, 571, 601, 631, 641, 673, 743, 811, 911, 1151, 1361, 1621, 1693, 1973, 2243, 2393, 3083, 3163, 3181, 3343, 3461, 3821, 3923, 4481, 4523, 4561, 4591, 4663, 4861, 4903, 5051, 5261
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OFFSET
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1,1
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COMMENTS
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Primes p such that 3*p+8 and 9*p+32 are also primes. - Vincenzo Librandi, Aug 04 2010
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LINKS
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FORMULA
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a(n) == 1 or 3 (mod 10) for n >= 2. - John Cerkan, Sep 13 2016
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MATHEMATICA
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Select[Range@ 5280, Times @@ Boole@ PrimeQ@ NestList[3 # + 8 &, #, 2] > 0 &] (* Michael De Vlieger, Sep 13 2016 *)
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PROG
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(Magma) [n: n in [0..100000] | IsPrime(n) and IsPrime(3*n+8) and IsPrime(9*n+32)] // 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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