Checking convergence of $\sum_{n=2}^{\infty} \frac{1}{(n\log(n))^p}$ $$\sum_{n=2}^{\infty} \frac{1}{(n\log(n))^p}.$$
Let
$$a_{n}:=  \frac{1}{(n\log(n))^p}$$
for $p \leq 0 $ divergent by $n^{th}$ term test.
for $p>0$ $a_n$ is non negative decreasing
We'll use the Cauchy Condensation test
$$\sum_{n=2}^{\infty} \frac{2^n}{(2^n\log(2^n))^p} = \sum_{n=2}^{\infty} \frac{2^n}{2^{np}n^p (\log(2))^p} = \frac{1}{(\log(2))^p}\sum_{n=2}^{\infty} \frac{2^n}{2^{np}n^p}$$
$$ (\frac{2^n}{2^{np}n^p})^{1/n} = \frac{1}{2^{p-1}n^{p/n}} \to \frac{1}{2^{p-1}}$$
For convergence $$\frac{1}{2^{p-1}} < 1 \Rightarrow p-1>0 \Rightarrow p >1 $$
and divergent for $0<p<1$
for $p=1$
$$\sum_{n=2}^{\infty} \frac{1}{n\log(n)} $$ diverges by integral test.
Conclusion : Converges if $p>1$ otherwise diverges
Is this argument fine?
 A: I'm a bit rusty on the Cauchy Condensation test. But here is an alternative solution, perhaps this will be of some use. 
Let $a_k=\bigg( \frac{1}{k\ln k} \bigg)^p$
First, if $p\leqq 0 $ clearly $a_k \not\rightarrow 0$ as $k\rightarrow \infty$ and thus $\sum_{k=2}^{\infty} a_k$ diverges.
Now choose $b_k=\frac{1}{k(\ln k)^p}$ such that $\sum_{k=2}^{\infty} b_k$ is convergent for $p>1$ and divergent for $p \in (0,1]$. This follows from the integral test since $b_k$ is positive and decreasing $\forall k\in[2,\infty]$.
Note that in general if $|\frac{a_k}{b_k}| \longrightarrow 0, k\longrightarrow \infty$ it means that $\forall \epsilon>0$ $ \exists$ $M>0$ such that $|a_k| < \epsilon|b_k|$ when $k>M$ and if $\sum a_k$ and $\sum b_k$ are both positive series, we therefore know that $\sum b_k$ convergent $\implies$ $\sum a_k$ convergent by the comparison test.
In the same manner, we have that if $|\frac{a_k}{b_k}| \longrightarrow \infty, k\longrightarrow \infty$ $\implies$ $\forall N>0$ $\exists$ $M>0$ such that $|\frac{a_k}{b_k}| > N $ if $k>M$ and therefore $\sum b_k$ divergent $\implies \sum a_k$ diverges.
In our case, fix $p\in(0,1)$, then $|\frac{a_k}{b_k}| = \frac{1}{k^{p-1}} \longrightarrow \infty, k \longrightarrow \infty$ and because we know that $\sum b_k$ diveriges for $p\in(0,1)$ so does $\sum a_k$ (since both $a_k,b_k$ are non negative). If $p=1$ we use the integral test as above.
Now fix $p>1$ we have $|\frac{a_k}{b_k}| = \frac{1}{k^{p-1}} \longrightarrow 0, k \longrightarrow \infty$ and since $\sum b_k$ converges for these $p$, so does $\sum a_k$.
Thus, $\sum_{k=2}^{\infty}\bigg( \frac{1}{k\ln k} \bigg)^p$ converges $\forall$ $p>1$.
