M000000724

$$\pi=8\arctan\left(\frac{1}{3}\right)+4\arctan\left(\frac{1}{4}\right)-4\arctan\left(\frac{1}{5}\right)+4\arctan\left(\frac{1}{9}\right)-4\arctan\left(\frac{1}{60}\right)+4\arctan\left(\frac{1}{3107}\right)$$