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 A023304 #30 Dec 05 2024 11:39:49 %S A023304 13,31,181,541,661,1087,1861,2179,2719,3727,7459,8089,8707,9109,10639, %T A023304 17341,19333,22501,23293,29287,32797,39847,40387,42703,46591,51613, %U A023304 53101,56149,56809,57829,59233,80779,87643,89113,89413,91291,93979,94261,98899 %N A023304 Primes that remain prime through 4 iterations of function f(x) = 2x + 5. %C A023304 Primes p such that 2*p+5, 4*p+15, 8*p+35 and 16*p+75 are also primes. - _Vincenzo Librandi_, Aug 04 2010 %H A023304 John Cerkan, <a href="/A023304/b023304.txt">Table of n, a(n) for n = 1..10000</a> %F A023304 a(n) == 1 (mod 6). - _John Cerkan_, Sep 27 2016 %t A023304 Select[Prime@ Range[10^4], Times @@ Boole@ PrimeQ@ Rest@ NestList[2 # + 5 &, #, 4] > 0 &] (* _Michael De Vlieger_, Sep 27 2016 *) %t A023304 Select[Prime[Range[10000]],AllTrue[Rest[NestList[2#+5&,#,4]],PrimeQ]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Oct 23 2020 *) %o A023304 (Magma) [n: n in [1..1000000] | IsPrime(n) and IsPrime(2*n+5) and IsPrime(4*n+15) and IsPrime(8*n+35) and IsPrime(16*n+75)]; // _Vincenzo Librandi_, Aug 04 2010 %Y A023304 Subsequence of A023205, A023243, A023274, and A089038. %K A023304 nonn %O A023304 1,1 %A A023304 _David W. Wilson_ %E A023304 Definition clarified by _Harvey P. Dale_, Oct 23 2020