fermat_last_theorem

Fermat's Last Theorem. For every integer $n \geq 3$, the equation $a^n + b^n = c^n$ has no solutions in positive integers $a, b, c$.

Proved by Andrew Wiles (with Richard Taylor) in 1994–1995 for $n$ an odd prime, combined with Fermat's own 1640 proof for $n = 4$.