M000000723

$$\pi=8\arctan\left(\frac{1}{2}\right)-4\arctan\left(\frac{1}{4}\right)+4\arctan\left(\frac{1}{5}\right)-4\arctan\left(\frac{1}{9}\right)+4\arctan\left(\frac{1}{60}\right)-4\arctan\left(\frac{1}{3107}\right)$$