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 A023245 #28 Sep 08 2022 08:44:47 %S A023245 5,11,19,31,59,61,71,101,109,151,179,239,241,269,281,389,409,439,449, %T A023245 521,571,641,659,719,829,911,971,1051,1061,1181,1201,1229,1319,1361, %U A023245 1439,1579,1669,1699,1741,1831,1949,2269,2341,2371,2521,2549,2579,2609,2671 %N A023245 Primes that remain prime through 2 iterations of the function f(x) = 2x + 9. %C A023245 Primes p such that 2*p+9 and 4*n+27 are also primes. - _Vincenzo Librandi_, Aug 04 2010 %H A023245 John Cerkan, <a href="/A023245/b023245.txt">Table of n, a(n) for n = 1..10000</a> %t A023245 Select[Prime[Range[500]],And@@PrimeQ[Rest[NestList[2#+9&,#,2]]]&] (* _Harvey P. Dale_, Mar 23 2011 *) %o A023245 (Magma) [n: n in [0..100000] | IsPrime(n) and IsPrime(2*n+9) and IsPrime(4*n+27)] // _Vincenzo Librandi_, Aug 04 2010 %o A023245 (PARI) isok(n) = isprime(n) && isprime(2*n+9) && isprime(4*n+27); \\ _Michel Marcus_, Sep 12 2016 %Y A023245 Subsequence of A023207 and A155722. %K A023245 nonn %O A023245 1,1 %A A023245 _David W. Wilson_