A145488 Numbers k such that 6k+13 is prime and 12k+13 is also prime.

0, 4, 5, 8, 14, 15, 19, 25, 28, 30, 33, 35, 44, 49, 50, 54, 60, 68, 70, 85, 88, 93, 99, 100, 103, 120, 123, 133, 140, 144, 145, 149, 154, 168, 170, 173, 175, 179, 184, 190, 198, 215, 228, 235, 245, 253, 259, 264, 268, 274, 275, 280, 285, 288, 294

Offset: 1

Author

Artur Jasinski, Oct 11 2008

Keywords

• nonn

Links

• Ivan Neretin, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A063908-A063913, A092109, A145471-A145490.

Programs

Maple

select(k -> isprime(6*k+13) and isprime(12*k+13), [$0..1000]); # Robert Israel, Jan 23 2017

Mathematica

aa = {}; k = 13; Do[If[PrimeQ[(k + Prime[n])/2], AppendTo[aa, (Prime[n] - k)/12]], {n, 1, 500}]; aa

Formula

a(n) = (A145474(n)-13)/12.

Extensions

Definition corrected by Ivan Neretin, Jan 23 2017