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A063909
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Primes p such that 2*p - 5 is also prime.
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6
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5, 11, 17, 23, 29, 47, 53, 59, 71, 89, 101, 131, 137, 149, 179, 197, 227, 233, 257, 263, 281, 311, 353, 383, 389, 401, 431, 443, 467, 479, 491, 509, 557, 593, 599, 617, 641, 647, 653, 683, 719, 743, 809, 821, 857, 863, 941, 947, 953, 977, 1109
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OFFSET
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1,1
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COMMENTS
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All terms are == 5 (mod 6). - Zak Seidov, Jan 07 2014
There are several interesting computer generated conjectures for this sequence at Jon Maiga's Sequence Machine site. - Antti Karttunen, Dec 07 2021
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LINKS
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FORMULA
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EXAMPLE
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29 is in the sequence since p = 29 is prime and 2*p - 5 = 53 is also prime.
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MATHEMATICA
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Select[Prime[Range[500]], PrimeQ[2#-5]&] (* Harvey P. Dale, Oct 10 2011 *)
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PROG
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(PARI) { n=0; p=1; for (m=1, 10^9, p=nextprime(p+1); if (isprime(2*p - 5), write("b063909.txt", n++, " ", p); if (n==1000, break)) ) } \\ Harry J. Smith, Sep 02 2009
(PARI) isA063909(p) = ((p%2)&&isprime(p)&&isprime(p+p-5)); \\ Antti Karttunen, Dec 07 2021
(Magma) [p: p in PrimesUpTo(2000) | IsPrime(2*p-5)]; // Vincenzo Librandi, Feb 25 2016
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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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