Machin-like formulae
M000393
$$\pi=16\arctan\left(\frac{1}{7}\right)+16\arctan\left(\frac{1}{18}\right)-4\arctan\left(\frac{1}{239}\right)$$
Compact formula
16[7] + 16[18] - 4[239]
Lehmer's measure
2.40038
References
STØRMER (1896)
(full reference coming soon)