A220296 Number of n-digit composites with n-digit home primes.
0, 1, 24, 194, 1457, 11027, 86978, 716526, 5948091, 50665173
Offset: 1
Examples
21=3*7 and 37 is prime, and no other composite 2-digit number has a 2-digit home prime; so a(2)=1. Starting with a composite implies at least 2 digits, so a(1)=0 trivially.
Links
- Wikipedia, Home prime
Extensions
a(9) and a(10) added by James G. Merickel, Jun 28 2015
Comments