Apéry's theorem

Apéry's theorem is a result in number theory that concerns the value of the Riemann zeta function at positive integer values. Specifically, the theorem states that the value \(\zeta(3)\), the Riemann zeta function evaluated at 3, is not a rational number. The theorem was proven by Roger Apéry in 1979 and is significant because it was one of the first results to demonstrate that certain values of the zeta function are irrational.