A139440 - OEIS

%I #15 Dec 29 2016 02:33:40

%S 3,4,5,7,12,15,26,31,50,71,186,273,366,1542,1929,3687,4407,15395,15433

%N Numbers n such that primorial(n)/2 - 4 is prime.

%C a(20) > 25000. - _Robert Price_, Dec 03 2016

%t k = 1; a = {}; Do[k = k*Prime[n]; If[PrimeQ[k - 4], Print[n]; AppendTo[a, n]], {n, 2, 366}]; a

%Y Cf. A067026, A067027, A139439-A139457, A103514.

%K nonn

%O 1,1

%A _Artur Jasinski_, Apr 21 2008

%E a(14)-a(15) from _Ray Chandler_, Jun 16 2013

%E a(16)-a(17) from _Robert Price_, Aug 16 2016

%E a(18) from _Robert Price_, Dec 03 2016

%E Added missing term, 15395 by _Robert Price_, Dec 28 2016