Let $\mathbb{N}=\{1,2,\cdots\}$. Does there exist a bijective function $\pi:\mathbb{N} \to \mathbb{N}$ such that $$\sum_{n=1}^{\infty}\dfrac{\pi{(n)}}{n^2}<\infty ?$$
My try: note $$\sum_{n=1}^{\infty}\dfrac{1}{n^2} $$ is convergent,
and then I can't. Thank you.