Machin-like formulae
M000255
$$\pi=96\arctan\left(\frac{1}{53}\right)+80\arctan\left(\frac{1}{57}\right)-20\arctan\left(\frac{1}{239}\right)+48\arctan\left(\frac{1}{4443}\right)$$
Compact formula
96[53] + 80[57] - 20[239] + 48[4443]
Lehmer's measure
1.84406
References
Chien-Lih, Hwang. More Machin-type identities,
The Mathematical Gazette
81, 120–121, 1997. [DOI:
10.2307/3618793
]
ARNDT (1993)
(full reference coming soon)
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