A120222 Numbers k such that 6+k and 6*k+1 are prime.

1, 5, 7, 11, 13, 17, 23, 25, 35, 37, 47, 55, 61, 73, 77, 83, 91, 95, 101, 103, 107, 121, 125, 131, 143, 151, 161, 173, 175, 187, 205, 217, 221, 233, 245, 257, 263, 271, 277, 287, 305, 311, 325, 331, 347, 367, 373, 391, 395, 425, 443, 451, 455, 461, 481, 503, 551

Offset: 1

Author

Zak Seidov, Jun 10 2006

Keywords

• nonn

Comments

All terms == 1 or 5 (mod 6). - Robert Israel, Oct 29 2020

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A120226, A120227, A120228, A106057-A106066.

Programs

Maple

select(n -> isprime(n+6) and isprime(6*n+1), [seq(i,i=1..1000,2)]); # Robert Israel, Oct 29 2020

Mathematica

Select[Range[551],PrimeQ[#+6]&&PrimeQ[6#+1]&] (* James C. McMahon, Sep 26 2024 *)