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 A130699 #7 Nov 12 2014 13:04:16
%S A130699 6,9,12,15,18,21,24,26,27,30,33,36,39,42,44,45,48,51,54,57,59,60,61,
%T A130699 63,66,69,72,75,78,79,81,84,86,87,90,93,96,99,102,103,105,106,108,109,
%U A130699 111,114,117,120,123,125,126,128,129,131,132,135,138,141,144,146
%N A130699 Numbers n for which neither 2n-3 nor 2n+3 are primes.
%e A130699 Not 5 because 7 and 13 are prime, but 6 because neither 9 nor 15 are primes.
%t A130699 Select[Range[200],NoneTrue[2#+{3,-3},PrimeQ]&] (* The program uses the NoneTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Nov 12 2014 *)
%o A130699 (PARI) isok(n) = !isprime(2*n-3) && !isprime(2*n+3) \\ _Michel Marcus_, Jul 11 2013
%Y A130699 Cf. A104278.
%K A130699 easy,nonn
%O A130699 2,1
%A A130699 _W. Neville Holmes_, Jul 11 2007
%E A130699 Missing term 24 added by _Michel Marcus_, Jul 11 2013