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A057326
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First member of a prime triple in a 2p-1 progression.
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28
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2, 19, 79, 331, 439, 499, 619, 829, 1069, 1279, 1531, 2089, 2131, 2179, 2311, 2791, 3019, 3061, 3109, 3181, 3769, 4159, 4231, 4261, 4621, 4639, 4861, 4951, 5419, 5749, 6121, 6211, 6709, 6841, 7369, 7411, 7561, 7639, 8209, 8629, 9109, 9199, 9319, 9739, 10321, 10831
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OFFSET
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1,1
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COMMENTS
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Numbers n such that n remains prime through 2 iterations of function f(x) = 2x - 1.
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LINKS
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EXAMPLE
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Triplets are (2,3,5), (19,37,73), (79,157,313), (331,661,1321), ...
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MAPLE
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select(p -> andmap(isprime, [p, 2*p-1, 4*p-3]), [seq(p, p=0..10000)]); # K. D. Bajpai, Jun 26 2017
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MATHEMATICA
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Select[Prime[Range[1500]], And@@PrimeQ[NestList[2#-1&, #, 2]]&] (* Harvey P. Dale, Dec 09 2011 *)
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PROG
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(PARI) forprime(p= 1, 100000, if(isprime(2*p-1) && isprime(4*p-3), print1(p, ", "))); \\ K. D. Bajpai, Jun 26 2017
(Magma) [p: p in PrimesUpTo (10000) | IsPrime(2*p-1) and IsPrime(4*p-3)]; // K. D. Bajpai, Jun 26 2017
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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