Infinite product

Summary

An infinite product $\prod_{n=1}^{\infty} a_n$ is the multiplicative analogue of a series: it is the sequence of partial products $a_1 a_2 \cdots a_N$. Its value, when it converges, is the limit of these partial products. Infinite products express many classical functions and constants, such as the Wallis product for $\pi$ and the Euler product formula for the zeta function. The exact definition is in infinite product.