A237810 - OEIS

%I #16 Sep 08 2022 08:46:06

%S 2,3,5,11,23,41,53,83,113,131,173,191,251,281,293,593,641,683,743,953,

%T 1031,1103,1451,1481,1601,2003,2063,2141,2393,2693,2903,3023,3413,

%U 3593,3623,3761,3821,3911,4211,4373,4481,4733,4871,5081,5303,5441,5741,5903

%N Primes p such that 2*p+1 and 2*p+7 are also prime.

%H Vincenzo Librandi, <a href="/A237810/b237810.txt">Table of n, a(n) for n = 1..1000</a>

%e 11 is in the sequence because 11, 2*11+1 = 23 and 2*11+7 = 29 are all prime.

%t Select[Prime[Range[10000]], PrimeQ[2 # + 1]&&PrimeQ[2 # + 7]&] (* _Vincenzo Librandi_, Feb 15 2014 *)

%o (PARI) s=[]; forprime(p=2, 10000, if(isprime(2*p+1) && isprime(2*p+7), s=concat(s, p))); s

%o (Magma) [p: p in PrimesUpTo(9200) | IsPrime(2*p+1) and IsPrime(2*p+7)]; // _Vincenzo Librandi_, Feb 15 2014

%Y Cf. A126107, A237811, A237812, A237813, A237814.

%K nonn,easy

%O 1,1

%A _Colin Barker_, Feb 13 2014