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 A168080 #16 Jul 10 2016 02:40:08
%S A168080 0,1,2,3,9,12,15,18,21,22,26,28,30,32,34,38,39,42,45,46,50,56,58,60,
%T A168080 62,64,68,69,72,74,76,80,81,82,86,98,99,102,105,108,111,112,128,129,
%U A168080 130,134,136,138,140,148,150,152,154,160,164,165,166,170,176,178,180,182
%N A168080 Numbers n such that exactly two of n+-1, n+-2 and n+-3 are primes.
%H A168080 G. C. Greubel, <a href="/A168080/b168080.txt">Table of n, a(n) for n = 1..1000</a>
%t A168080 okQ[n_]:=Length[Select[Drop[Range[n-3,n+3],{4}],PrimeQ]]==2; Join[{0,1}, Select[Range[0,200],okQ]] (* _Harvey P. Dale_, Jun 29 2011 *)
%Y A168080 Cf. A000040, A100317.
%K A168080 nonn
%O A168080 1,3
%A A168080 _Juri-Stepan Gerasimov_, Nov 18 2009
%E A168080 Corrected (14 removed, 58, 62, 74 inserted, etc.) by _R. J. Mathar_, Jun 04 2010