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%I #13 Sep 08 2022 08:45:47
%S 5,11,19,31,41,61,71,109,151,211,229,269,379,419,431,439,479,619,641,
%T 709,739,809,839,971,1009,1069,1229,1259,1319,1361,1439,1451,1499,
%U 1531,1579,1669,1801,1879,1889,2011,2111,2239,2269,2381,2411,2551,2579,2591
%N Primes p such that 7*p-6 and 7*p+6 are also prime numbers.
%C Primes of the form A087681(k)/7, any index k.
%H Vincenzo Librandi, <a href="/A164566/b164566.txt">Table of n, a(n) for n = 1..1000</a>
%F A136052 INTERSECT A023225. [R. J. Mathar, Aug 20 2009]
%e For p=5, both 7*5-6=29 and 7*5+6=41 are prime,
%e for p=11, both 7*11-6=71 and 7*11+6=83 are prime.
%t lst={};Do[p=Prime[n];If[PrimeQ[7*p-6]&&PrimeQ[7*p+6],AppendTo[lst,p]], {n,6!}];lst
%t Select[Prime[Range[700]], And @@ PrimeQ/@{7 # + 6, 7 # - 6}&] (* _Vincenzo Librandi_, Apr 09 2013 *)
%o (Magma) [p: p in PrimesUpTo(3000) | IsPrime(7*p-6) and IsPrime(7*p+6)]; // _Vincenzo Librandi_, Apr 09 2013
%o (PARI) is(n)=isprime(n) && isprime(7*n-6) && isprime(7*n+6) \\ _Charles R Greathouse IV_, Mar 28 2017
%Y Cf. A106015, A125272, A127430, A046133, A087681, A136052, A023225.
%K nonn,easy
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, Aug 16 2009
%E Examples rephrased by _R. J. Mathar_, Aug 20 2009
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