$$ \arctan(x) = \arctan(1) + \arctan\left(\frac{x-1}{2}\right) - \arctan\left(\frac{(x-1)^2}{4} \right) + \arctan\left(\frac{(x-1)^3}{8}\right) - \cdots $$
Is this known?
Sums of arctangents
Michael Hardy
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- 85
- 126