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%I #20 Sep 08 2022 08:44:47
%S 13,139,293,1889,2939,3719,6089,7741,12823,19753,21391,22861,28513,
%T 36721,37967,40949,60899,76519,83621,101747,121687,127549,128239,
%U 142099,149197,153817,155581,158489,160159,169283,173651,180749,185831,192037,198221
%N Primes that remain prime through 4 iterations of function f(x) = 10x + 9.
%C Primes p such that 10*p+9, 100*p+99, 1000*p+999 and 10000*p+9999 are also primes. - _Vincenzo Librandi_, Aug 04 2010
%H John Cerkan, <a href="/A023329/b023329.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) == 9 or 13 (mod 14). - _John Cerkan_, Oct 09 2016
%t Select[Prime[Range[20000]],AllTrue[Rest[NestList[10#+9&,#,4]],PrimeQ]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Feb 16 2020 *)
%o (Magma) [n: n in [1..5000000] | IsPrime(n) and IsPrime(10*n+9) and IsPrime(100*n+99) and IsPrime(1000*n+999) and IsPrime(10000*n+9999)] // _Vincenzo Librandi_, Aug 04 2010
%Y Subsequence of A023240, A023270, A023301, and A102700.
%K nonn
%O 1,1
%A _David W. Wilson_
%E Definition clarified by _Harvey P. Dale_, Feb 16 2020
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