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 A139441 #11 Jan 01 2017 17:38:08
%S A139441 2,3,4,5,9,11,12,18,24,29,38,76,146,152,187,200,404,442,504,950,2796,
%T A139441 5133,5683,11334,13775,20539,21253
%N A139441 Numbers n such that primorial(n)/2 + 8 is prime.
%C A139441 a(28) > 25000. - _Robert Price_, Jan 01 2017
%t A139441 k = 1/2; a = {}; Do[k = k*Prime[n]; If[PrimeQ[k + 8], Print[n]; AppendTo[a, n]], {n, 404}]; a
%t A139441 (* Second program *)
%t A139441 Select[Range[10^3], PrimeQ[(Times @@ Prime@ Range@ #)/2 + 8] &] (* _Michael De Vlieger_, Jan 01 2017 *)
%Y A139441 Cf. A067026, A067027, A139439-A139457, A103514.
%K A139441 nonn
%O A139441 1,1
%A A139441 _Artur Jasinski_, Apr 21 2008
%E A139441 a(18)-a(21) from _Ray Chandler_, Jun 16 2013
%E A139441 a(22)-a(27) from _Robert Price_, Jan 01 2017