A023318 - OEIS

%I #20 Sep 10 2025 18:41:04

%S 1319,2699,4259,4919,5689,8669,10159,10529,29819,33119,82339,86689,

%T 98669,174079,177949,196739,207869,210599,222499,231809,253369,267299,

%U 275699,323699,362459,371639,378179,388529,397799,402529,421079,448859,468499

%N Primes that remain prime through 4 iterations of function f(x) = 7x + 6.

%C Primes p such that 7*p+6, 49*p+48, 343*p+342 and 2401*p+2400 are also primes. - _Vincenzo Librandi_, Aug 04 2010

%H John Cerkan, <a href="/A023318/b023318.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) == 9 (mod 10). - _John Cerkan_, Oct 08 2016

%o (Magma) [n: n in [1..1000000] | IsPrime(n) and IsPrime(7*n+6) and IsPrime(49*n+48) and IsPrime(343*n+342) and IsPrime(2401*n+2400)]; // _Vincenzo Librandi_, Aug 04 2010

%Y Subsequence of A023225, A023259, A023290, and A024900.

%K nonn

%O 1,1

%A _David W. Wilson_