A109617 Numbers k such that (10's complement factorial of k) - 1 is prime.

2, 3, 4, 7, 77, 337, 397, 566, 615, 822, 1007, 1017, 1073, 1351, 1731, 2635, 6606, 8513, 10404

Offset: 1

Author

Jason Earls, Aug 01 2005

Keywords

• nonn
• base
• hard
• more

Examples

			3 is a term because (10-3)*(10-2)*(10-1) - 1 = 503 is prime.
77 is a term because (100-77)*..*(100-10)*(10-9)*..*(10-1) - 1 is prime.
		

Crossrefs

Cf. A109616, A110396.

Extensions

a(9)-a(17) from Jinyuan Wang, Aug 09 2025

a(18)-a(19) from Michael S. Branicky, Aug 13 2025