%I #32 Sep 08 2022 08:44:47

%S 2,5,7,11,17,19,23,29,31,37,43,59,61,67,73,101,103,109,137,149,173,

%T 191,193,197,199,211,227,229,233,239,263,269,271,283,331,337,353,359,

%U 367,373,379,383,401,409,449,467,479,499,523,541,557,569,607,613,617,647,673,683

%N Primes p such that 10*p + 3 is also prime.

%H John Cerkan, <a href="/A023238/b023238.txt">Table of n, a(n) for n = 1..10000</a>

%p A023238:=n->`if`(isprime(n) and isprime(10*n+3), n, NULL): seq(A023238(n), n=1..10^3); # _Wesley Ivan Hurt_, Sep 08 2016

%t Select[Prime[Range[200]], PrimeQ[10# + 3] &] (* _Alonso del Arte_, Jun 24 2014 *)

%o (Magma) [n: n in [0..1000] | IsPrime(n) and IsPrime(10*n+3)] // _Vincenzo Librandi_, Nov 20 2010

%Y Cf. A023239.

%Y Subsequence of A102338.

%K nonn

%O 1,1

%A _David W. Wilson_