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A139441
Numbers n such that primorial(n)/2 + 8 is prime.
6
2, 3, 4, 5, 9, 11, 12, 18, 24, 29, 38, 76, 146, 152, 187, 200, 404, 442, 504, 950, 2796, 5133, 5683, 11334, 13775, 20539, 21253
OFFSET
1,1
COMMENTS
a(28) > 25000. - Robert Price, Jan 01 2017
MATHEMATICA
k = 1/2; a = {}; Do[k = k*Prime[n]; If[PrimeQ[k + 8], Print[n]; AppendTo[a, n]], {n, 404}]; a
(* Second program *)
Select[Range[10^3], PrimeQ[(Times @@ Prime@ Range@ #)/2 + 8] &] (* Michael De Vlieger, Jan 01 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Artur Jasinski, Apr 21 2008
EXTENSIONS
a(18)-a(21) from Ray Chandler, Jun 16 2013
a(22)-a(27) from Robert Price, Jan 01 2017
STATUS
approved