M000000664

$$\pi=-16\arctan\left(\frac{1}{2}\right)+16\arctan\left(\frac{1}{4}\right)+16\arctan\left(\frac{1}{5}\right)+28\arctan\left(\frac{1}{8}\right)+8\arctan\left(\frac{1}{247057}\right)-4\arctan\left(\frac{1}{740943}\right)$$