M000003524

$$\pi=12\arctan\left(\frac{1}{5}\right)-4\arctan\left(\frac{1}{6}\right)+12\arctan\left(\frac{1}{15}\right)+12\arctan\left(\frac{1}{21}\right)-4\arctan\left(\frac{1}{31}\right)+4\arctan\left(\frac{1}{57}\right)+12\arctan\left(\frac{1}{81}\right)-12\arctan\left(\frac{1}{467}\right)$$