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 A138620 #14 Dec 09 2019 08:18:13
%S A138620 1,2,4,5,6,7,9,11,14,15,16,19,20,21,22,26,29,30,32,35,36,37,39,40,41,
%T A138620 42,47,49,50,54,55,57,60,62,69,70,72,74,76,79,81,82,85,86,91,92,96,97,
%U A138620 99,102,105,107,109,110,114,119,120,121,124,125,126,127,130
%N A138620 Nonnegative integers n such that 12*n-1 is prime.
%H A138620 Daniel Starodubtsev, <a href="/A138620/b138620.txt">Table of n, a(n) for n = 1..10000</a>
%e A138620 12*1-1=11, 12*2-1=23, 12*4-1=47, 12*5-1=59, ...
%t A138620 a={};Do[x=12*n-1;If[PrimeQ[x],AppendTo[a,n]],{n,10^2}];a
%t A138620 Select[Range[500],PrimeQ[12#-1]&] (* _Harvey P. Dale_, May 14 2011 *)
%Y A138620 Cf. A068231 (resulting primes).
%K A138620 nonn
%O A138620 1,2
%A A138620 _Vladimir Joseph Stephan Orlovsky_, May 14 2008
%E A138620 More terms from _Harvey P. Dale_, May 14 2011