Hey guys.
I wrote the problem in word, it's much easier for me
Thanks in advance.
You'll be famous if you succeed. $\displaystyle \sum_{n=1}^\infty\frac1{n^3}$ is Apéry's constant, for which there is no known closed form. Even less is known about $\displaystyle \sum_{n=1}^\infty\frac1{n^5}$.