# Retkes, Zoltan

## Inequality for square summable complex series ★★

Author(s): Retkes

\begin{conjecture} For all $\alpha=(\alpha_1,\alpha_2,\ldots)\in l_2(\cal{C})$ the following inequality holds $$\sum_{n\geq 1}|\alpha_n|^2\geq \frac{6}{\pi^2}\sum_{k\geq0}\bigg| \sum_{l\geq0}\frac{1}{l+1}\alpha_{2^k(2l+1)}\bigg|^2$$

\end{conjecture}

Keywords: Inequality