A139448 Numbers n such that primorial(n)/2 - 64 is prime.

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

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 * A356398 A364803 A022561

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