M000061

$$\pi=532\arctan\left(\frac{1}{239}\right)+728\arctan\left(\frac{1}{1252}\right)+928\arctan\left(\frac{1}{2855}\right)+400\arctan\left(\frac{1}{58898}\right)+248\arctan\left(\frac{1}{110443}\right)+552\arctan\left(\frac{1}{4841182}\right)$$
Compact formula532[239] + 728[1252] + 928[2855] + 400[58898] + 248[110443] + 552[4841182]
Lehmer's measure1.59018
References
Chien-Lih, Hwang. More Machin-type identities, The Mathematical Gazette 81, 120–121, 1997. [DOI: 10.2307/3618793]

HCL (14Feb95)(ΒΆΒΆ1.96453) (full reference coming soon)