Euler product for Riemann zeta
From specialfunctionswiki
Theorem (Euler Product): The following formula holds for $\mathrm{Re}(z)>1$: $$\zeta(z)=\displaystyle\sum_{n=1}^{\infty} \dfrac{1}{n^z} = \displaystyle\prod_{p \mathrm{\hspace{2pt} prime}} \dfrac{1}{1-p^{-z}},$$ where $\zeta$ is the Riemann zeta function.
Proof: █
