M000000959

$$\pi=8\arctan\left(\frac{1}{4}\right)-8\arctan\left(\frac{1}{5}\right)+20\arctan\left(\frac{1}{7}\right)-8\arctan\left(\frac{1}{86}\right)+8\arctan\left(\frac{1}{939}\right)+8\arctan\left(\frac{1}{1068}\right)-8\arctan\left(\frac{1}{1764383}\right)$$