A023214 - OEIS

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

%S 2,3,17,23,47,59,83,101,107,113,149,167,191,233,251,257,281,311,401,

%T 443,449,467,503,521,569,593,617,647,653,677,761,827,839,857,863,881,

%U 941,947,971,1013,1031,1049,1109,1163,1181,1277,1301,1307,1319,1361,1409,1433

%N Primes p such that 4*p + 5 is also prime.

%C Except for the first two terms, all terms are congruent to 5 (mod 6). - _John Cerkan_, Sep 07 2016

%H John Cerkan, <a href="/A023214/b023214.txt">Table of n, a(n) for n = 1..10000</a>

%p A023214:=n->`if`(isprime(n) and isprime(4*n+5), n, NULL): seq(A023214(n), n=1..3*10^3); # _Wesley Ivan Hurt_, Sep 07 2016

%t Select[Prime[Range[250]],PrimeQ[4#+5]&] (* _Harvey P. Dale_, Oct 21 2018 *)

%o (Magma) [n: n in [0..100000] | IsPrime(n) and IsPrime(4*n+5)] // _Vincenzo Librandi_, Aug 04 2010

%Y Subsequence of A111215. - _Michel Marcus_, Jul 08 2016

%K nonn

%O 1,1

%A _David W. Wilson_