A023224 Primes p such that 7*p + 4 is also prime.

7, 19, 37, 61, 79, 97, 139, 151, 157, 211, 229, 271, 307, 349, 379, 457, 487, 547, 571, 601, 607, 619, 631, 709, 751, 757, 769, 829, 877, 907, 937, 997, 1021, 1069, 1117, 1129, 1237, 1249, 1291, 1327, 1429, 1447, 1471, 1489, 1549, 1567, 1579, 1621, 1627, 1699

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Comments

Subsequence of A024902. All terms are congruent to 1 mod 6 because 7(6n + 5) + 4 is divisible by 3. - John Cerkan, Jul 08 2016

Links

• John Cerkan, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A024902.

Programs

Magma

[n: n in [0..100000] | IsPrime(n) and IsPrime(7*n+4)] // Vincenzo Librandi, Nov 19 2010

Maple

A023224:=n->`if`(isprime(n) and isprime(7*n+4), n, NULL): seq(A023224(n), n=1..5000); # Wesley Ivan Hurt, Jul 08 2016

Mathematica

Select[Prime[Range[300]], PrimeQ[7# + 4] &] (* Alonso del Arte, Nov 21 2018 *)

PARI

lista(nn) = for(p=2, nn, if(isprime(7*p+4), print1(p, ", "))); \\ Altug Alkan, Jul 08 2016