A109758 Numbers k such that (10's complement factorial of k) - 1 is semiprime.

5, 6, 10, 13, 20, 22, 23, 24, 27, 29, 33, 40, 41, 43, 46, 51, 54, 79, 80, 83, 85, 93, 106, 111

Offset: 1

Author

Jason Earls, Aug 12 2005

Keywords

• more
• nonn
• base

Comments

Sequence possibly continues with 112, 137, 145, 148, 163, 165, 177, 190, 196, 197. 206 is the next certain term. - Tyler Busby, Feb 09 2023

Crossrefs

Cf. A110396, A109617.

Extensions

More terms from Sean A. Irvine, Sep 18 2012