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 A123980 #12 Mar 27 2020 09:00:20
%S A123980 12,24,57,162,234,249,267,297,432,519,564,717,969,984,1167,1179,1389,
%T A123980 1734,2007,2364,2427,2544,2664,2769,2784,3582,3627,3819,3897,4089,
%U A123980 4287,5244,5307,5337,5472,5577,5667,5727,5967,6084,6102,6399,6522,6822,6987
%N A123980 Numbers k for which 8*k+1, 8*k+5 and 8*k+7 are primes.
%H A123980 Amiram Eldar, <a href="/A123980/b123980.txt">Table of n, a(n) for n = 1..10000</a>
%t A123980 Select[Range[7000], And @@ PrimeQ /@ ({1, 5, 7} + 8#) &] (* _Ray Chandler_, Nov 05 2006 *)
%Y A123980 Cf. A005122, A005123, A005124, A105133.
%K A123980 nonn
%O A123980 1,1
%A A123980 _Artur Jasinski_, Oct 30 2006
%E A123980 Extended by _Ray Chandler_, Nov 05 2006