A023341 Primes that remain prime through 5 iterations of function f(x) = 5x + 2.

135859, 174877, 192979, 244219, 292561, 679297, 842341, 964897, 1076029, 1470241, 1990579, 2004943, 2339263, 2615707, 2625577, 2633557, 2892277, 3003787, 3201901, 3758233, 4406797, 5065861, 5157547, 5390857, 5424961, 5546173, 5875369, 7746217

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Comments

Primes p such that 5*p+2, 25*p+12, 125*p+62, 625*p+312 and 3125*p+1562 are also primes. - Vincenzo Librandi, Aug 05 2010

Numbers k such that A280720(k) > 4. - Felix Fröhlich, Jan 07 2017

Links

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

Crossrefs

Subsequence of A023217, A023252, A023283, A023313, and A111223.

Cf. A280720.

Programs

Magma

[n: n in [1..10000000] | IsPrime(n) and IsPrime(5*n+2) and IsPrime(25*n+12) and IsPrime(125*n+62) and IsPrime(625*n+312) and IsPrime(3125*n+1562)] // Vincenzo Librandi, Aug 05 2010

Mathematica

p5Q[n_]:=And@@PrimeQ/@NestList[5#+2&,n,5]
Select[Prime[Range[550000]],p5Q]  (* Harvey P. Dale, Feb 17 2011 *)

Formula

a(n) == 31 (mod 42). - John Cerkan, Oct 17 2016