%I #46 Sep 08 2022 08:45:04
%S 5,11,17,23,29,47,53,59,71,89,101,131,137,149,179,197,227,233,257,263,
%T 281,311,353,383,389,401,431,443,467,479,491,509,557,593,599,617,641,
%U 647,653,683,719,743,809,821,857,863,941,947,953,977,1109
%N Primes p such that 2*p - 5 is also prime.
%C All terms are == 5 (mod 6). - _Zak Seidov_, Jan 07 2014
%C There are several interesting computer generated conjectures for this sequence at _Jon Maiga_'s Sequence Machine site. - _Antti Karttunen_, Dec 07 2021
%H Antti Karttunen, <a href="/A063909/b063909.txt">Table of n, a(n) for n = 1..25000</a> (first 1000 terms from Harry J. Smith)
%H Jon Maiga, <a href="http://sequencedb.net/s/A063909">Computer-generated formulas for A063909</a>, Sequence Machine.
%F Intersection of A089253 and A000040. - _Michael B. Porter_, Jan 07 2014
%F a(n) = (A145471(n)+5)/2. [Also listed by Sequence Machine, and obviously true] - _Antti Karttunen_, Dec 07 2021
%e 29 is in the sequence since p = 29 is prime and 2*p - 5 = 53 is also prime.
%t Select[Prime[Range[500]],PrimeQ[2#-5]&] (* _Harvey P. Dale_, Oct 10 2011 *)
%o (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
%o (PARI) isA063909(p) = ((p%2)&&isprime(p)&&isprime(p+p-5)); \\ _Antti Karttunen_, Dec 07 2021
%o (Magma) [p: p in PrimesUpTo(2000) | IsPrime(2*p-5)]; // _Vincenzo Librandi_, Feb 25 2016
%Y Cf. A000040, A089253, A145471.
%Y Subsequence of A016969.
%K nonn
%O 1,1
%A _N. J. A. Sloane_, Aug 31 2001