A128658 Numbers k such that p(k+1)# - p(k)# + 1 is prime where p(i)# = product of first i primes = A002110(i).

1, 3, 7, 14, 80, 224, 280, 287, 652, 1509, 2952, 3915, 7771

Offset: 1

Author

Pierre CAMI, Mar 19 2007

Keywords

• nonn
• more

Crossrefs

Cf. A002110, A128420, A128421, A128657, A128659, A128660, A128661, A128662.

Programs

PARI

isok(n) = {my(pp=prod(k=1, n, prime(k))); isprime(pp*prime(n+1) - pp + 1);} \\ Michel Marcus, Sep 20 2019

Extensions

a(13) from Michael S. Branicky, Oct 06 2024