By Abel's theorem, what is ∑n=1∞(−1)n−1n\sum_{n=1}^{\infty} \frac{(-1)^{n-1}}{n}∑n=1∞n(−1)n−1, given that ∑n=1∞(−1)n−1nxn\sum_{n=1}^{\infty} \frac{(-1)^{n-1}}{n} x^n∑n=1∞n(−1)n−1xn converges at x=1x=1x=1?
ln2\ln 2ln2
1−ln21 - \ln 21−ln2
π4\frac{\pi}{4}4π
e−2e - 2e−2