A128421 Numbers n such that p(n)# + p(n+1)# +1 is prime, where p(n)# is the product of first n primes (A002110).

2, 3, 4, 5, 6, 8, 20, 56, 101, 108, 141, 202, 265, 364, 401, 1035, 1588, 3062, 4191, 4579

Offset

1,1

Links

Table of n, a(n) for n=1..20.

Prog

(PARI) pd(n)=prod(i=1, n, prime(i)) \\ A002110
for(k=1, 10^4, a=pd(k)+pd(k+1)+1; if(isprime(a), print1(k, ", "))) \\ Alexandru Petrescu, Jun 17 2022

Crossrefs

Cf. A002110, A014545, A128420.

Sequence in context: A364455 A358175 A241947 * A115885 A259390 A345900

Adjacent sequences: A128418 A128419 A128420 * A128422 A128423 A128424

Keyword

nonn,more

Author

Pierre CAMI, Mar 02 2007

Extensions

Corrected by Emeric Deutsch, Mar 06 2007

Edited by Ray Chandler, Mar 13 2007

Status

approved