M000000163

$$\pi=64\arctan\left(\frac{1}{21}\right)+28\arctan\left(\frac{1}{239}\right)-16\arctan\left(\frac{1}{769}\right)-16\arctan\left(\frac{2}{433287}\right)$$

Compact formula	`64[21] + 28[239] - 16[769] - 16[433287/2]`
Lehmer's measure	1.71067
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 MRW on 2 August 2009.] Download references as BibTeΧ