The number $\zeta (3)=\sum _1^{\infty }{n}^{-3}$, where ζ‎ denotes the zeta function. Exact values of ζ‎(n), for even positive n, were determined by Euler and are rational multiples of π‎ⁿ. But very little is known for odd n. In 1978 Roger Apéry showed ζ‎(3) to be irrational, but it remains unknown whether the constant is transcendental.