Machin-like formulae
M000335
$$\pi=48\arctan\left(\frac{1}{38}\right)+80\arctan\left(\frac{1}{57}\right)+28\arctan\left(\frac{1}{239}\right)+96\arctan\left(\frac{1}{268}\right)$$
Compact formula
48[38] + 80[57] + 28[239] + 96[268]
Lehmer's measure
2.03480
References
GAUSS (1876)
(full reference coming soon)