|
%I #13 Sep 29 2017 21:30:02
%S 3,4,5,6,7,8,9,11,13,16,20,27,39,83,103,122,129,145,279,393,608,798,
%T 929,1164,1266,1491,2043,3276,3426,7119,15711,18424
%N (Prime(n)# - 4)/2 is prime, where x# is the primorial A034386(x).
%C n such that A002110(n)/2 - 2 is prime.
%C a(33) > 25000. - _Robert Price_, Sep 29 2017
%t p = 1; Do[p = p*Prime[n]; If[PrimeQ[(p - 4)/2], Print[n]], {n, 1, 400} ]
%t Flatten[Position[Rest[FoldList[Times,1,Prime[Range[2100]]]],_?(PrimeQ[(#-4)/2]&)]] (* _Harvey P. Dale_, Nov 22 2014 *)
%Y Cf. A002110, A067024, A067027.
%K nonn
%O 1,1
%A _Labos Elemer_, Dec 29 2001
%E More terms from _Robert G. Wilson v_, Dec 30 2001
%E a(21)-a(27) from _Ray Chandler_, Jun 16 2013
%E a(28)-a(32) from _Robert Price_, Sep 29 2017
|
