M000000966

$$\pi=8\arctan\left(\frac{1}{4}\right)+12\arctan\left(\frac{1}{7}\right)-8\arctan\left(\frac{1}{27}\right)-8\arctan\left(\frac{1}{57}\right)-8\arctan\left(\frac{1}{86}\right)+8\arctan\left(\frac{1}{939}\right)-8\arctan\left(\frac{1}{1764383}\right)$$