This is getting on my nerves now. I am stumped on these: 1. The problem statement, all variables and given/known data Obtain an expression for: phi(p^3) and phi(P^n) 2. Relevant equations phi(p^2)=p(p-1) 3. The attempt at a solution The factors of P^n are 1 and P. Any number less than P^n that shares a factor must have p as a factor. there are 3 numbers less than p^n. These are 1, P, and P^2. Therefore phi(P^n)=P^n-3 But that is completely wrong, and I feel that I need lots of help. Also, if I can obtain an expression for phi(P^n) that might help me with phi(p^3).