M000003580

$$\pi=4\arctan\left(\frac{1}{2}\right)+8\arctan\left(\frac{1}{3}\right)-4\arctan\left(\frac{1}{5}\right)+4\arctan\left(\frac{1}{18}\right)-4\arctan\left(\frac{1}{21}\right)-8\arctan\left(\frac{1}{23}\right)-4\arctan\left(\frac{1}{47}\right)-8\arctan\left(\frac{1}{83}\right)$$

Compact formula	`4[2] + 8[3] - 4[5] + 4[18] - 4[21] - 8[23] - 4[47] - 8[83]`
Lehmer's measure	10.2549