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A139448 Numbers n such that primorial(n)/2 - 64 is prime. 5
4, 5, 6, 7, 10, 13, 17, 18, 28, 32, 35, 38, 89, 115, 117, 224, 241, 353, 440, 1153, 2585, 3075, 3456, 4895, 7483, 7649, 8197, 8625, 13285, 19849, 24179, 24442 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(33) > 25000. - Robert Price, Apr 10 2017

LINKS

Table of n, a(n) for n=1..32.

MATHEMATICA

k = 1; a = {}; Do[k = k*Prime[n]; If[PrimeQ[k - 64]&&k>64, Print[n]; AppendTo[a, n]], {n, 2, 325}]; a

Flatten[Position[Rest[FoldList[Times, 1, Prime[Range[600]]]], _?(PrimeQ[ #/2-64]&&#/2>64&)]] (* Harvey P. Dale, Mar 05 2013 *)

Select[Range[4, 100], PrimeQ[Product[Prime[k], {k, 1, #}]/2 - 64] &] (* Robert Price, Apr 10 2017 *)

CROSSREFS

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

Sequence in context: A107756 A080723 A288737 * A022561 A213524 A047312

Adjacent sequences:  A139445 A139446 A139447 * A139449 A139450 A139451

KEYWORD

nonn

AUTHOR

Artur Jasinski, Apr 21 2008

EXTENSIONS

a(18)-a(19) from Harvey P. Dale, Mar 05 2013

Drop 2 and correct programs, a(20)-a(21) from Ray Chandler, Jun 16 2013

a(22)-a(32) from Robert Price, Apr 10 2017

STATUS

approved

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Last modified January 24 18:53 EST 2022. Contains 350565 sequences. (Running on oeis4.)