A067006 Smallest number for which the totient is divisible by the n-th nontotient number, that is, the n-th term of A007617.
7, 11, 29, 19, 23, 53, 29, 31, 103, 191, 43, 47, 101, 53, 81, 59, 311, 67, 103, 71, 149, 191, 79, 83, 173, 181, 283, 197, 101, 103, 107, 121, 229, 709, 367, 311, 127, 131, 269, 137, 139, 569, 293, 149, 151, 229, 463, 317, 163, 167, 1021, 173, 349, 179, 181, 547
Offset: 1
Keywords
Examples
14 = A007617(7) is not totient of any other number, but phi(29) = 28 is divisible by 14 and 29 is the smallest number of which the totient is a multiple of 14, so a(7)=29.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Formula
a(n) = min_{x : mod(phi(x), A007617(n)) = 0}. For all nontotient numbers x, q*x+1 is prime with large enough q and a divisor of phi(q*x+1) = q*x is x, the selected nontotient number. [Corrected by Sean A. Irvine, Nov 28 2023]