M000003585

$$\pi=16\arctan\left(\frac{1}{5}\right)-4\arctan\left(\frac{1}{7}\right)+8\arctan\left(\frac{1}{12}\right)+16\arctan\left(\frac{1}{21}\right)-16\arctan\left(\frac{1}{32}\right)-16\arctan\left(\frac{1}{60}\right)-8\arctan\left(\frac{1}{70}\right)+16\arctan\left(\frac{1}{3107}\right)$$