M000000496

$$\pi=8\arctan\left(\frac{1}{4}\right)+12\arctan\left(\frac{1}{7}\right)-8\arctan\left(\frac{1}{21}\right)-8\arctan\left(\frac{1}{57}\right)$$

Compact formula	`8[4] + 12[7] - 8[21] - 8[57]`
Lehmer's measure	4.17007