M000003497

$$\pi=12\arctan\left(\frac{1}{5}\right)+4\arctan\left(\frac{1}{8}\right)+4\arctan\left(\frac{1}{12}\right)+12\arctan\left(\frac{1}{21}\right)-12\arctan\left(\frac{1}{32}\right)-12\arctan\left(\frac{1}{60}\right)-4\arctan\left(\frac{1}{70}\right)+12\arctan\left(\frac{1}{3107}\right)$$