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Primes that remain prime through 5 iterations of function f(x) = 5x + 2.
3

%I #27 Sep 08 2022 08:44:47

%S 135859,174877,192979,244219,292561,679297,842341,964897,1076029,

%T 1470241,1990579,2004943,2339263,2615707,2625577,2633557,2892277,

%U 3003787,3201901,3758233,4406797,5065861,5157547,5390857,5424961,5546173,5875369,7746217

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

%C 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

%C Numbers k such that A280720(k) > 4. - _Felix Fröhlich_, Jan 07 2017

%H John Cerkan, <a href="/A023341/b023341.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) == 31 (mod 42). - _John Cerkan_, Oct 17 2016

%t p5Q[n_]:=And@@PrimeQ/@NestList[5#+2&,n,5]

%t Select[Prime[Range[550000]],p5Q] (* _Harvey P. Dale_, Feb 17 2011 *)

%o (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

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

%Y Cf. A280720.

%K nonn

%O 1,1

%A _David W. Wilson_