There might be an incorrect formula mentioned in the article Kronecker delta on Wikipedia.
The formula I'm talking about is this:
$\delta_{nm}=\lim_{N\rightarrow\infty}\frac{1}{N}\sum_{k=1}^Ne^{2\pi i\frac{k}{N}\left(n-m\right)}$
After I simplified this formula (the right side), because I saw that there was $e^{\pi i}$ which could be turned into $-1$, it came out so that $\delta_{nm}=1$ which is obviously incorrect. So I'd like you guys to look into it just in case I'm wrong.
