About $\lim_{n \rightarrow \infty} \prod_{1 \leq i \leq n}\left( 1-\frac{1}{p_i} \right)$ where $p_i$ is the ith prime
Let$\ p_n$ be the$\ n$-th prime. Can you give me a proof for$\ \prod_{i=1}^\infty \frac{p_i-1}{p_i}=P\approx \frac{1}{11.0453}$?