# Testing convergence of $\sum\limits_{n=2}^{\infty} \frac{\cos{\log{n}}}{n \cdot \log{n}}$

Does the series: $$\sum\limits_{n=2}^{\infty} \frac{\cos(\log{n})}{n \cdot \log{n}}$$ converge or diverge?

I know that $|\cos(\log{n})| \leq 1$, but I really cannot apply it here. Any ideas on how to attack this problem

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A quick try using $|\cos(\log{n})| \leq 1$ and the integral test gives that the $n$th partial sum is $\leq log(log(n))$, so if this diverges it does so very slowly. – Alex Becker Mar 23 '11 at 1:55
On the other hand, the positive and negative terms "should" cancel each other out for the most part. I expect convergence. – Michael Lugo Mar 23 '11 at 1:59
I expect it to converge... Probably try a variation of generalized alternate test (Dirichlet test)? – user17762 Mar 23 '11 at 2:01

The search was series "cos(log(n))".