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 A139454 #9 Jul 03 2017 02:13:04
%S A139454 5,6,9,10,11,12,17,18,23,36,48,62,87,112,131,400,1606,6136,6519,11700
%N A139454 Numbers n such that primorial(n)/2 - 512 is prime.
%C A139454 a(21) > 25000. - _Robert Price_, Jul 02 2017
%t A139454 k = 1; a = {}; Do[k = k*Prime[n]; If[PrimeQ[k - 512]&&k>512, Print[n]; AppendTo[a, n]], {n, 2, 325}]; a (* corrected by _Ray Chandler_, Jun 16 2013 *)
%Y A139454 Cf. A067026, A067027, A139439-A139457, A103514.
%K A139454 nonn
%O A139454 1,1
%A A139454 _Artur Jasinski_, Apr 21 2008
%E A139454 Dropped 2 and a(16)-a(17) from _Ray Chandler_, Jun 16 2013
%E A139454 a(18)-a(20) from _Robert Price_, Jul 02 2017