# The most difficult problem that no one can solve! :)

Calculus Level 4

Let $$s=\sigma+it\in C$$ and $$\sigma>1$$. Define $$\zeta(s)=\sum_{n=1}^\infty\frac{1}{n^{s}}$$.

Evaluate $$\lim_{s \rightarrow 1}(1-s) \frac{\zeta'(s)}{\zeta(s)}$$.

×