A023240 Primes p such that 10*p + 9 is also prime.

2, 5, 7, 13, 17, 19, 23, 37, 41, 43, 47, 59, 61, 71, 73, 83, 101, 103, 127, 131, 139, 149, 157, 197, 199, 223, 233, 239, 257, 269, 271, 281, 293, 307, 311, 331, 349, 353, 373, 401, 409, 421, 433, 463, 467, 479, 491, 499, 503, 509, 541, 547, 563, 577, 587, 593, 607, 619

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

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

Crossrefs

Subsequence of A102700.

Programs

Magma

[ n: n in PrimesUpTo(700) | IsPrime(10*n+9) ]; // Vincenzo Librandi, Nov 20 2010

Mathematica

Select[Prime@ Range@ 120, PrimeQ[10 # + 9] &] (* Michael De Vlieger, Sep 12 2016 *)