$x^{n}+y^{n} \neq z^{n}$ for $n \geq 3$
[ \sum{n=1}^\infty \frac{1}{n} \text{ is divergent, but } \lim{n \to \infty} \sum_{i=1}^n \frac{1}{i} - \ln n \text{exists.} ]
… できない