A118223 Numbers k such that k! * prime(k)# - 1 is prime.

2, 3, 4, 9, 11, 12, 13, 50, 73, 81, 82, 115, 308, 405, 3818, 4608

Offset

1,1

Comments

Fourteen terms found and primes proved by PrimeForm ([N+1, Brillhart-Lehmer-Selfridge]).

Links

Table of n, a(n) for n=1..16.

Example

3 is a term as 3! * prime(3)# - 1 = 3*2*1 * 5*3*2 - 1 = 179, a prime.

Crossrefs

Cf. A002110, A118222.

Sequence in context: A068334 A283874 A263092 * A359219 A212989 A211546

Adjacent sequences: A118220 A118221 A118222 * A118224 A118225 A118226

Keyword

nonn,more

Author

Rick L. Shepherd, Apr 16 2006

Extensions

a(15)-a(16) from Michael S. Branicky, Dec 14 2023

Status

approved