\frac{1}{\epsilon} +1\\N(\epsilon)=E( \frac{1}{\epsilon} +1)+1/" alt="|\frac{n}{n^2-1}\cos\frac{\pi}{n} |\le\frac{n+1}{n^2-1} \le\frac{1}{n-1} <\epsilon\\n>\frac{1}{\epsilon} +1\\N(\epsilon)=E( \frac{1}{\epsilon} +1)+1/" align="absmiddle" class="latex-formula">