  Let $g(p)$ denote the least primitive root modulo $p$, and $h(p)$ the least
primitive root modulo $p^2$. We computed $g(p)$ and $h(p)$ for all primes $p\le
10^{16}$. Here we present the results of that computation and prove three
theorems as a consequence. In particular, we show that $g(p)<p^{5/8}$ for all
primes $p>3$ and that $h(p)<p^{2/3}$ for all primes $p$.
