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 A127957 #12 Jul 07 2018 19:27:27
%S A127957 10,12,13,15,16,17,19,20,21,23,24,25,27,28,29,30,32,33,34,35,36,37,38,
%T A127957 40,41,42,44,45,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,
%U A127957 66,67,68,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89
%N A127957 Numbers k such that (2^prime(k) + 1)/3 is composite.
%H A127957 G. C. Greubel, <a href="/A127957/b127957.txt">Table of n, a(n) for n = 1..1175</a>
%t A127957 a = {}; Do[c = (2^Prime[x] + 1)/3; If[PrimeQ[c] == False, AppendTo[a, x]], {x, 2, 300}]; a
%t A127957 Select[Range[2,100],!PrimeQ[(2^Prime[#]+1)/3]&] (* _Harvey P. Dale_, Nov 24 2013 *)
%o A127957 (PARI) isok(n) = (n!=1) && !isprime((2^prime(n)+1)/3); \\ _Michel Marcus_, Jul 07 2018
%Y A127957 Cf. A000979, A000978, A124400, A126614, A127955, A127956.
%K A127957 nonn
%O A127957 1,1
%A A127957 _Artur Jasinski_, Feb 09 2007