[ \sum_{n=1}^{\infty} \frac{n!}{n^n}, \quad \sum_{n=1}^{\infty} \frac{(-1)^n}{\sqrt{n} + \ln n} ] Determine convergence/divergence, find sum where possible.
I understand you’re looking for a (a well-known author in Peruvian and Latin American engineering/mathematics circles).