Machin-like formulae
M000457: Hermann's formula
$$\pi=8\arctan\left(\frac{1}{2}\right)-4\arctan\left(\frac{1}{7}\right)$$
Name
Hermann's formula
Compact formula
8[2] - 4[7]
Lehmer's measure
4.50522
References
HERMANN (1706)(ΒΆΒΆ6.60113)
(full reference coming soon)