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A139449
Numbers n such that primorial(n)/2 + 128 is prime.
5
2, 4, 5, 7, 8, 10, 11, 23, 25, 67, 87, 125, 141, 242, 255, 258, 279, 316, 449, 578, 871, 1072, 1886, 2071, 3315, 18225
OFFSET
1,1
COMMENTS
a(27) > 25000. - Robert Price, Apr 10 2017
MATHEMATICA
k = 1/2; a = {}; Do[k = k*Prime[n]; If[PrimeQ[k + 128], Print[n]; AppendTo[a, n]], {n, 325}]; a
Select[Range[0, 25000], PrimeQ[Product[Prime[k], {k, 1, #}]/2 + 128] &] (* Robert Price, Apr 10 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Artur Jasinski, Apr 21 2008
EXTENSIONS
a(18)-a(24) from Ray Chandler, Jun 16 2013
a(25)-a(26) from Robert Price, Apr 10 2017
STATUS
approved