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 A023244 #27 Sep 08 2022 08:44:47 %S A023244 2,5,17,23,53,83,137,197,227,257,293,317,347,383,467,593,647,677,683, %T A023244 797,857,953,1163,1193,1217,1607,1877,1907,1913,1997,2063,2207,2237, %U A023244 2843,2903,3023,3257,3323,3557,3947,4133,4253,4517,4583,4643,4967,5087,5387 %N A023244 Primes that remain prime through 2 iterations of the function f(x) = 2x + 7. %C A023244 Primes p such that 2*p+7 and 4*p+21 are also primes. - _Vincenzo Librandi_, Aug 04 2010 %H A023244 John Cerkan, <a href="/A023244/b023244.txt">Table of n, a(n) for n = 1..10000</a> %F A023244 a(n) == 5 (mod 6), for n > 1. - _John Cerkan_, Sep 12 2016 %t A023244 Select[Prime@ Range[10^3], Times @@ Boole@ PrimeQ@ NestList[2 # + 7 &, #, 2] > 0 &] (* _Michael De Vlieger_, Sep 12 2016 *) %o A023244 (Magma) [n: n in [0..100000] | IsPrime(n) and IsPrime(2*n+7) and IsPrime(4*n+21)] // _Vincenzo Librandi_, Aug 04 2010 %Y A023244 Subsequence of A023206 and A105760. %K A023244 nonn %O A023244 1,1 %A A023244 _David W. Wilson_