I tried to calculate the sum of the following series without success, any clue would be helpful!
$$\sum_{n=2}^\infty \ln\left(1+\frac{(-1)^n}{n}\right) $$
Answer
Hint:
$$\prod_{n=2}^{2N}\left(1+\frac{(-1)^n}{n}\right)=\prod_{m=1}^{N}\left(1+\frac{1}{2m}\right)\prod_{m=1}^{N-1}\left(1-\frac{1}{2m+1}\right)=\frac{2N+1}{2N}=1+\frac{1}{2N}. $$
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