Abstract:
In this paper the author establishes the existence of a series
$\sum a_{\nu_k}\cos\nu_kx+b_{\nu_k}\sin\nu_kx$ in some rearranged trigonometric system, which converges everywhere to a Lebesgue integrable function and whose coefficients $a_{\nu_k}$ and $b_{\nu_k}$, $k=1,2,\dots$, are not the Fourier–Lebesgue coefficients of this function. Similar results are established for the Haar system and some other systems.
Bibliography: 17 titles.