M000003559

$$\pi=12\arctan\left(\frac{1}{5}\right)+12\arctan\left(\frac{1}{15}\right)+12\arctan\left(\frac{1}{21}\right)-8\arctan\left(\frac{1}{23}\right)-8\arctan\left(\frac{1}{30}\right)-4\arctan\left(\frac{1}{38}\right)+12\arctan\left(\frac{1}{81}\right)-12\arctan\left(\frac{1}{467}\right)$$