M000000428

$$\pi=24\arctan\left(\frac{1}{10}\right)+12\arctan\left(\frac{1}{18}\right)+8\arctan\left(\frac{1}{100}\right)+8\arctan\left(\frac{1}{307}\right)-12\arctan\left(\frac{1}{515}\right)+8\arctan\left(\frac{1}{9901}\right)$$