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 A023307 #21 Sep 08 2022 08:44:47 %S A023307 1129,10009,11489,12539,13859,30029,63079,77359,99119,121039,124669, %T A023307 169409,194749,205589,246329,330329,349519,351829,354839,361279, %U A023307 369539,384589,395719,399769,416989,429109,446819,527599,532489,544259,575119 %N A023307 Primes that remain prime through 4 iterations of function f(x) = 3x + 2. %C A023307 Primes p such that 3*p+2, 9*p+8, 27*p+26, and 81*p+80 are also primes. - _Vincenzo Librandi_, Aug 04 2010 %H A023307 John Cerkan, <a href="/A023307/b023307.txt">Table of n, a(n) for n = 1..10000</a> %F A023307 a(n) == 9 or 69 (mod 70). - _John Cerkan_, Oct 04 2016 %t A023307 Select[Prime[Range[50000]],AllTrue[Rest[NestList[3#+2&,#,4]],PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Oct 13 2015 *) %o A023307 (Magma) [n: n in [1..1000000] | IsPrime(n) and IsPrime(3*n+2) and IsPrime(9*n+8) and IsPrime(27*n+26) and IsPrime(81*n+80)] // _Vincenzo Librandi_, Aug 04 2010 %Y A023307 Subsequence of A023208, A023246, A023277, and A024893. %K A023307 nonn %O A023307 1,1 %A A023307 _David W. Wilson_