Wallis's Product/Also presented as

Wallis's Product: Also presented as

Wallis's Product can also be seen presented as:

$\ds \prod_{n \mathop = 1}^\infty \frac n {n - \frac 1 2} \cdot \frac n {n + \frac 1 2} = \frac \pi 2$

Some sources present it as:

$\ds \prod_{n \mathop = 1}^\infty \frac {4 n^2} {4 n^2 - 1} = \frac \pi 2$

which follows from the given form by an application of Difference of Two Squares on the denominator of the product.