A237811 - OEIS

%I #11 Sep 08 2022 08:46:06

%S 2,5,11,29,131,179,239,281,359,491,641,659,719,761,809,911,1229,1439,

%T 1481,1811,2549,2699,2819,3299,3449,3491,4211,4349,4481,5051,5279,

%U 5441,5639,5741,6101,6269,6449,6581,6899,7121,7211,7541,7649,7691,8111,8741,8951

%N Primes p such that 2*p+1 and 2*p+9 are also prime.

%H Vincenzo Librandi, <a href="/A237811/b237811.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+9 = 31 are all prime.

%t Select[Prime[Range[10000]], PrimeQ[2 # + 1]&&PrimeQ[2 # + 9]&] (* _Vincenzo Librandi_, Feb 15 2014 *)

%o (PARI) s=[]; forprime(p=2, 10000, if(isprime(2*p+1) && isprime(2*p+9), s=concat(s, p))); s

%o (Magma) [p: p in PrimesUpTo(9200) | IsPrime(2*p+1) and IsPrime(2*p+9)]; // _Vincenzo Librandi_, Feb 15 2014

%Y Cf. A126107, A237810, A237812, A237813, A237814.

%K nonn,easy

%O 1,1

%A _Colin Barker_, Feb 13 2014