Machin-like formulae
M000000615
$$\pi=8\arctan\left(\frac{1}{2}\right)-4\arctan\left(\frac{1}{4}\right)+4\arctan\left(\frac{1}{18}\right)+4\arctan\left(\frac{1}{34}\right)+4\arctan\left(\frac{1}{55}\right)$$
Compact formula
8[2] - 4[4] + 4[18] + 4[34] + 4[55]
Lehmer's measure
7.00708