Prove that phee(n) is even for any n greater than or equal to 3 (here phee(n) is the Euler phee-
function).
What do you know about $\displaystyle \phi$ ?
If you know that for $\displaystyle n=p_1^{k_1}.. p_r^{k_r}$ , then:
$\displaystyle \phi(n)=(p_1-1)p^{k_1-1}..(p_r-1)p^{k_r-1}.$
And it follows immeadiatly that if $\displaystyle n>2$ that $\displaystyle \phi $ is even (as if it has an odd prime factor $\displaystyle p_i$, then $\displaystyle (p_i-1)$ is even and so $\displaystyle \phi(n)$ is even, or if it only has even prime factors then it is a power k of 2 greater than the first and $\displaystyle 2^{k-1}$ is even)
ZB