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 A178642 #11 Jan 09 2021 02:47:56
%S A178642 3,29,37,43,47,59,61,67,73,79,83,89,97,101,107,109,113,127,131,137,
%T A178642 139,149,151,157,163,173,179,181,191,193,197,199,211,223,227,229,233,
%U A178642 239,241,251,257,263,269,271,277,281,283,293,307,311,313,317,331,337,347
%N A178642 Primes p such that primorial(p)/2 - 2 is not prime.
%e A178642 3*5*7*11*13*17*19*23*29 - 2 = 43*167*450473 is composite.
%t A178642 pp=1;lst={};Do[p=Prime[n];pp*=p;If[ !PrimeQ[pp-2],AppendTo[lst,p]],{n,2,2*5!}];lst
%t A178642 Transpose[Select[With[{pros=Rest[FoldList[Times,1,Prime[Range[100]]]]}, Table[ {Prime[n], pros[[n]]},{n,100}]],!PrimeQ[Last[#]/2-2]&]][[1]] (* _Harvey P. Dale_, Mar 02 2012 *)
%Y A178642 Cf. A002110, A096177, A096547, A178641.
%K A178642 nonn
%O A178642 1,1
%A A178642 _Vladimir Joseph Stephan Orlovsky_, May 31 2010