A081711 Numbers k such that k! + k# - 1 is prime, where k# is the primorial function A034386(k).

2, 3, 4, 5, 8, 17, 23, 26, 35, 47, 82, 100, 147, 183, 271, 492, 708, 1116, 1538, 2491, 4207, 4468, 8147

Offset: 1

Author

Mike Oakes, Apr 04 2003

Keywords

• nonn
• more
• hard

Comments

Some of the larger entries may only correspond to probable primes.

Examples

			a(1)=2 because 2!+2#-1=3 is prime
		

Links

• Mike Oakes, Primo-factorials.
• Mike Oakes, Primo-factorials, message 12028 in primenumbers Yahoo group, Apr 3, 2003. [Cached copy]

Crossrefs

Cf. A034386, A081710, A081712, A081713.

Extensions

Offset and ordering corrected by Sean A. Irvine, Sep 18 2023

a(23) from Michael S. Branicky, May 06 2025