M000000589

$$\pi=8\arctan\left(\frac{1}{2}\right)-4\arctan\left(\frac{1}{6}\right)+4\arctan\left(\frac{1}{18}\right)-4\arctan\left(\frac{1}{31}\right)$$

Compact formula	`8[2] - 4[6] + 4[18] - 4[31]`
Lehmer's measure	6.07419