M000003519

$$\pi=4\arctan\left(\frac{1}{2}\right)+4\arctan\left(\frac{1}{5}\right)+4\arctan\left(\frac{1}{9}\right)+4\arctan\left(\frac{1}{21}\right)-4\arctan\left(\frac{1}{32}\right)-4\arctan\left(\frac{1}{60}\right)+4\arctan\left(\frac{1}{73}\right)+4\arctan\left(\frac{1}{3107}\right)$$