Let $z$ be a complex number. Consider $f_n(z)=\sum_{k=1}^n k^{-z}$.
Now I wonder : Are there infinitely many positive integer $n$ such that there exists a $z$ with $f_n(z)=0$ and $Re(z)>1$ ?
I know that such $z$ exists for $n=13$.
I strongly suggest you read this article by P. Borwein et al. (Experimental math, 2007), as well as this followup by Gonek and Ledoan.
\sumfor sums, not\Sigma. – Did Dec 20 '13 at 12:19