A163603 Numbers k such that prime(k) == 5 (mod 7).

3, 8, 15, 18, 24, 27, 32, 40, 50, 55, 58, 65, 76, 78, 85, 91, 97, 99, 108, 111, 123, 125, 128, 130, 135, 149, 154, 158, 164, 170, 180, 184, 191, 194, 200, 203, 207, 214, 216, 227, 229, 237, 242, 246, 252, 260, 266, 271

Offset: 1

Author

Juri-Stepan Gerasimov, Aug 01 2009

Keywords

• nonn

Comments

The asymptotic density of this sequence is 1/6 (by Dirichlet's theorem). - Amiram Eldar, Mar 01 2021

Links

• G. C. Greubel, Table of n, a(n) for n = 1..5000

Crossrefs

Cf. A000040, A000720, A045458.

Programs

Mathematica

Select[Range[300], Mod[Prime[#], 7] == 5 &] (* G. C. Greubel, Jul 29 2017 *)

PARI

isok(n) = (prime(n) % 7) == 5; \\ Michel Marcus, Jul 29 2017

Formula

a(n) = A000720(A045458(n)).

A000040(a(n)) = A045458(n).

Extensions

Remainder in definition corrected by R. J. Mathar, Aug 01 2009