%I A067027
%S A067027 1,2,3,4,6,10,11,12,15,17,29,48,63,77,88,187,190,338,1133,1311,1832,
%T A067027 2782
%N A067027 Numbers n such that (primorial(n) + 4)/2 is a prime.
%C A067027 Numbers n such that [A002110(n)/2]+2 is prime.
%C A067027 These primes are products of consecutive odd primes plus 2: 2+[3.5.7.....p(n)] 
               if n is here.
%C A067027 a(19)-a(22) are Fermat and Lucas PRPs. (Primorial(2782)+4)/2 has 10865 
               digits. PFGW Version 1.2.0 for Windows [FFT v23.8] Primality testing 
               (p(2782)#+4)/2 [N-1/N+1, Brillhart-Lehmer-Selfridge] Running N-1 
               test using base 5 Running N+1 test using discriminant 13, base 1+sqrt(13) 
               (p(2782)#+4)/2 is Fermat and Lucas PRP! - Jason Earls (zevi_35711(AT)yahoo.com), 
               Dec 12 2006
%t A067027 p = 1; Do[p = p*Prime[n]; If[PrimeQ[(p + 4)/2], Print[n]], {n, 1, 400} 
               ]
%Y A067027 Cf. A002110, A067024, A065026.
%Y A067027 Sequence in context: A122397 A047417 A066936 this_sequence A005457 A005453 
               A122907
%Y A067027 Adjacent sequences: A067024 A067025 A067026 this_sequence A067028 A067029 
               A067030
%K A067027 nonn
%O A067027 1,2
%A A067027 Labos E. (labos(AT)ana.sote.hu), Dec 29 2001
%E A067027 More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 30 2001
%E A067027 a(19)-a(22) from Jason Earls (zevi_35711(AT)yahoo.com), Dec 12 2006