M000000378

$$\pi=20\arctan\left(\frac{1}{7}\right)+8\arctan\left(\frac{1}{26}\right)-8\arctan\left(\frac{1}{2057}\right)$$

Compact formula	`20[7] + 8[26] - 8[2057]`
Lehmer's measure	2.19184
References	Wetherfield, Michael Roby and Chien-Lih, Hwang. Computing pi: Lists of Machin-type (inverse cotangent) identities for pi/4, [Online; accessed 04-February-2024], 2013. [web.archive.org/web/20240204042153/http] [Found by Leonhard Euler in 1779.] Download references as BibTeΧ