M000000492

$$\pi=16\arctan\left(\frac{1}{4}\right)-16\arctan\left(\frac{1}{21}\right)-4\arctan\left(\frac{1}{252}\right)-4\arctan\left(\frac{1}{4633}\right)$$

Compact formula	`16[4] - 16[21] - 4[252] - 4[4633]`
Lehmer's measure	3.10647