M000000240

$$\pi=68\arctan\left(\frac{1}{22}\right)+12\arctan\left(\frac{1}{172}\right)-8\arctan\left(\frac{1}{682}\right)-28\arctan\left(\frac{1}{5357}\right)$$

Compact formula	`68[22] + 12[172] - 8[682] - 28[5357]`
Lehmer's measure	1.81330
References	Chien-Lih, Hwang. More Machin-type identities, The Mathematical Gazette 81(490), 120–121, 1997. [DOI: 10.2307/3618793] [Found by Michael Roby Wetherfield in 1994.] Download references as BibTeΧ