A077189 Smallest concatenation 123...(k-1) k (k-1)...321 (a concatenation of natural numbers from 1 to k and back to 1) that is a multiple of 2n-1, or 0 if no such number exists.
1, 12321, 0, 12345654321, 12321, 121, 12345654321, 0
Offset: 1
Examples
a(5) = 12321 is a multiple of 9.
Links
- Jinyuan Wang, Table of n, a(n) for n = 1..11
Extensions
More terms from Franklin T. Adams-Watters, Jun 02 2006
Comments