M000000519

$$\pi=4\arctan\left(\frac{1}{3}\right)+8\arctan\left(\frac{1}{5}\right)+8\arctan\left(\frac{1}{21}\right)-4\arctan\left(\frac{1}{38}\right)$$

Compact formula	`4[3] + 8[5] + 8[21] - 4[38]`
Lehmer's measure	4.91588