Definition:Square-Free Integer

Definition
Let $n \in \Z$.

Then $n$ is square-free iff $n$ has no divisor which is the square of a prime.

That is, iff the prime decomposition $n = p_1^{k_1} p_2^{k_2} \ldots p_r^{k_r}$ is such that $\forall i: 1 \le i \le r: k_i = 1$.