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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(28) > 25000. - Robert Price, Jan 01 2017

LINKS

Table of n, a(n) for n=1..27.

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

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

Sequence in context: A176008 A143827 A100797 * A093305 A065817 A084542

Adjacent sequences:  A139438 A139439 A139440 * A139442 A139443 A139444

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

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Last modified January 25 01:49 EST 2020. Contains 331229 sequences. (Running on oeis4.)