Abstract:
The most interesting result of the paper is that for any two complementary subsets $A$ and $B$ of the set of positive odd integers there exists such a sequence $\{\alpha_k\}_{k=1}^\infty\subset[-1,1]$ that
\begin{gather*}
\forall\,m\in A:\text{ the series }\sum_{k=1}^\infty\alpha_k^m\text{ is convergent and}
\\
\forall\,m\in B:\text{ the series }\sum_{k=1}^\infty\alpha_k^m\text{ is divergent.}
\end{gather*}
Using the map $\overrightarrow{x}\longmapsto\|\overrightarrow{x}\|^{\lambda}\frac{\overrightarrow{x}}{\|\overrightarrow{x}\|}$ as a substitute of the power function, one can prove similar results for vectors and positive not necessarily integer exponents $\lambda$.
Fulltext:
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