A139454 Numbers n such that primorial(n)/2 - 512 is prime.

5, 6, 9, 10, 11, 12, 17, 18, 23, 36, 48, 62, 87, 112, 131, 400, 1606, 6136, 6519, 11700

Offset: 1

Author

Artur Jasinski, Apr 21 2008

Keywords

• nonn

Comments

a(21) > 25000. - Robert Price, Jul 02 2017

Crossrefs

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

Programs

Mathematica

k = 1; a = {}; Do[k = k*Prime[n]; If[PrimeQ[k - 512]&&k>512, Print[n]; AppendTo[a, n]], {n, 2, 325}]; a (* corrected by Ray Chandler, Jun 16 2013 *)

Extensions

Dropped 2 and a(16)-a(17) from Ray Chandler, Jun 16 2013

a(18)-a(20) from Robert Price, Jul 02 2017