Mean value theorems for a class of Dirichlet series

We obtain an asymptotic formula instead of the upper bounds of Chandrasekharan and Narasimhan (1964) and Lau (1999) for the mean square value of the error term associated with the Dedekind zeta-function of a cubic field $K_3$. We study also modular analogs of the classical divisor problems. Bibl. – 21 titles.