Definition:Primitive Root (Number Theory)

Definition
Let $a, n \in \Z^*_+$, that is, let $a$ and $n$ be positive integers.

Let the order of $a$ modulo $n$ be $\phi \left({n}\right)$, where $\phi \left({n}\right)$ is the Euler phi function of $n$.

Then $a$ is said to be a primitive root of $n$.