A023239 Primes p such that 10*p + 7 is also prime.

3, 13, 19, 31, 61, 67, 79, 97, 109, 127, 163, 199, 223, 229, 241, 277, 283, 313, 367, 379, 421, 433, 439, 463, 487, 523, 541, 547, 571, 619, 631, 673, 691, 751, 757, 787, 811, 823, 829, 853, 859, 883, 937, 967, 1033, 1093, 1117, 1171, 1237, 1249, 1291, 1303, 1321

Offset

1,1

Links

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

Formula

a(n) == 1 (mod 6), for n > 1. - John Cerkan, Sep 12 2016

Mathematica

Select[Prime[Range[200]], PrimeQ[10# + 7] &] (* Alonso del Arte, Jun 24 2014 *)

Prog

(Magma) [n: n in [0..1000] | IsPrime(n) and IsPrime(10*n+7)] // Vincenzo Librandi, Nov 20 2010

Crossrefs

Cf. A023238.

Subsequence of A102342.

Sequence in context: A117300 A023215 A185069 * A229494 A211438 A018621

Adjacent sequences: A023236 A023237 A023238 * A023240 A023241 A023242

Keyword

nonn

Author

David W. Wilson

Status

approved