M000003516

$$\pi=-32\arctan\left(\frac{1}{2}\right)+64\arctan\left(\frac{1}{5}\right)+32\arctan\left(\frac{1}{12}\right)+64\arctan\left(\frac{1}{21}\right)-32\arctan\left(\frac{1}{70}\right)+28\arctan\left(\frac{1}{239}\right)-16\arctan\left(\frac{1}{616}\right)+16\arctan\left(\frac{1}{3141}\right)$$