cp's OEIS Frontend

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

%I A128658 #11 Oct 07 2024 00:48:20
%S A128658 1,3,7,14,80,224,280,287,652,1509,2952,3915,7771
%N A128658 Numbers k such that p(k+1)# - p(k)# + 1 is prime where p(i)# = product of first i primes = A002110(i).
%o A128658 (PARI) isok(n) = {my(pp=prod(k=1, n, prime(k))); isprime(pp*prime(n+1) - pp + 1);} \\ _Michel Marcus_, Sep 20 2019
%Y A128658 Cf. A002110, A128420, A128421, A128657, A128659, A128660, A128661, A128662.
%K A128658 nonn,more
%O A128658 1,2
%A A128658 _Pierre CAMI_, Mar 19 2007
%E A128658 a(13) from _Michael S. Branicky_, Oct 06 2024