A139450 Numbers n such that primorial(n)/2 - 128 is prime.

6, 7, 17, 26, 32, 40, 43, 391, 435, 1509, 1629, 2906, 3525, 5670, 8586, 12103, 12528, 16682

Offset: 1

Author

Artur Jasinski, Apr 21 2008

Keywords

• nonn

Comments

a(19) > 25,000. - Robert Price, May 02 2017

Crossrefs

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

Programs

Mathematica

k = 1; a = {}; Do[k = k*Prime[n]; If[PrimeQ[k - 128]&&k>128, Print[n]; AppendTo[a, n]], {n, 2, 325}]; a

Extensions

Drop 3,4 and correct program, a(9)-a(12) from Ray Chandler, Jun 16 2013

a(13)-a(18) from Robert Price, May 02 2017