Machin-like formulae
M000342
$$\pi=16\arctan\left(\frac{1}{5}\right)-4\arctan\left(\frac{1}{238}\right)+4\arctan\left(\frac{1}{56883}\right)$$
Compact formula
16[5] - 4[238] + 4[56883]
Lehmer's measure
2.06175
References
STØRMER (1896)
(full reference coming soon)