This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A023329 #24 Aug 28 2024 14:49:04 %S A023329 13,139,293,1889,2939,3719,6089,7741,12823,19753,21391,22861,28513, %T A023329 36721,37967,40949,60899,76519,83621,101747,121687,127549,128239, %U A023329 142099,149197,153817,155581,158489,160159,169283,173651,180749,185831,192037,198221 %N A023329 Primes that remain prime through 4 iterations of function f(x) = 10x + 9. %C A023329 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 A023329 John Cerkan, <a href="/A023329/b023329.txt">Table of n, a(n) for n = 1..10000</a> %F A023329 a(n) == 9 or 13 (mod 14). - _John Cerkan_, Oct 09 2016 %t A023329 Select[Prime[Range[20000]],AllTrue[Rest[NestList[10#+9&,#,4]],PrimeQ]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Feb 16 2020 *) %o A023329 (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 A023329 Subsequence of A023240, A023270, A023301, and A102700. %K A023329 nonn %O A023329 1,1 %A A023329 _David W. Wilson_ %E A023329 Definition clarified by _Harvey P. Dale_, Feb 16 2020