Euler's criterion
= Euler's criterion
{c}
{wiki}
For an odd prime $p$ and $p\nmid a$,
$$
a^{(p-1)/2}\equiv\left(\frac ap\right)\pmod p.
$$
= Euler's criterion
{c}
{wiki}
For an odd prime $p$ and $p\nmid a$,
$$
a^{(p-1)/2}\equiv\left(\frac ap\right)\pmod p.
$$