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 A124486 #10 Mar 25 2020 06:50:54
%S A124486 2,3,12,15,42,45,87,117,120,147,210,330,477,507,612,705,780,792,945,
%T A124486 1002,1065,1170,1275,1347,1470,1680,1695,1797,1902,2175,2187,2205,
%U A124486 2460,2472,2667,3057,3087,4047,4137,4257,4530,4740,4770,5082,5157,5295,5775
%N A124486 Numbers k such that 2*k-1, 4*k-1 and 6*k-1 are primes.
%H A124486 Amiram Eldar, <a href="/A124486/b124486.txt">Table of n, a(n) for n = 1..10000</a>
%t A124486 Select[Range[6000], And @@ PrimeQ /@ ({2, 4, 6}*# - 1) &] (* _Ray Chandler_, Nov 21 2006 *)
%Y A124486 Cf. A124485-A124492.
%K A124486 nonn
%O A124486 1,1
%A A124486 _Artur Jasinski_, Nov 04 2006
%E A124486 Extended by _Ray Chandler_, Nov 21 2006