How does WolframAlpha derive series representations for $\pi$?

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Given this formula

$\pi = \frac{\log(-1)}{\sqrt{-1}}$

How does WolframAlpha derive these other series representations?

The only one I recognize is the Leibniz formula for $\pi$

$$4\sum_{k=0}^{\infty} \frac{(-1)^k}{1+2k}$$

pi