M000000968

$$\pi=16\arctan\left(\frac{1}{4}\right)-16\arctan\left(\frac{1}{27}\right)-16\arctan\left(\frac{1}{86}\right)-4\arctan\left(\frac{1}{213}\right)+16\arctan\left(\frac{1}{939}\right)+4\arctan\left(\frac{1}{1958}\right)-16\arctan\left(\frac{1}{1764383}\right)$$