M000001212

$$\pi=4\arctan\left(\frac{1}{2}\right)+12\arctan\left(\frac{1}{3}\right)-8\arctan\left(\frac{1}{5}\right)-8\arctan\left(\frac{1}{13}\right)-8\arctan\left(\frac{1}{21}\right)$$

Compact formula	`4[2] + 12[3] - 8[5] - 8[13] - 8[21]`
Lehmer's measure	8.50252