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A139452 Numbers n such that primorial(n)/2 - 256 is prime. 5
6, 8, 16, 27, 66, 74, 168, 253, 458, 1310, 2665, 2681, 2718, 2836, 4921, 7356, 11466 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(18) > 25000. - Robert Price, May 22 2017

LINKS

Table of n, a(n) for n=1..17.

MATHEMATICA

k = 1; a = {}; Do[k = k*Prime[n]; If[PrimeQ[k - 256]&&k>256, Print[n]; AppendTo[a, n]], {n, 2, 325}]; a

CROSSREFS

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

Sequence in context: A006583 A011989 A270821 * A245643 A299030 A127400

Adjacent sequences:  A139449 A139450 A139451 * A139453 A139454 A139455

KEYWORD

nonn

AUTHOR

Artur Jasinski, Apr 21 2008

EXTENSIONS

Drop 3,4 and correct program, a(9)-a(14) from Ray Chandler, Jun 16 2013

a(15)-a(17) from Robert Price, May 22 2017

STATUS

approved

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Last modified July 26 22:49 EDT 2021. Contains 346300 sequences. (Running on oeis4.)