Machin-like formulae
M000000510
$$\pi=16\arctan\left(\frac{1}{4}\right)-16\arctan\left(\frac{1}{21}\right)-8\arctan\left(\frac{1}{408}\right)+4\arctan\left(\frac{1}{1393}\right)$$
Compact formula
16[4] - 16[21] - 8[408] + 4[1393]
Lehmer's measure
3.11838