M000000504

$$\pi=16\arctan\left(\frac{1}{4}\right)-16\arctan\left(\frac{1}{21}\right)+4\arctan\left(\frac{1}{41}\right)-8\arctan\left(\frac{1}{70}\right)$$

Compact formula	`16[4] - 16[21] + 4[41] - 8[70]`
Lehmer's measure	3.57929