Exact analytical vacuum solutions of $ R^n $-gravity model depending on two variables

Abstract: In this paper we consider the metric power-law $f(R)\sim R^n $-gravity model for the four-dimensional metric tensor depending on two coordinates. We obtain exact analytical vacuum solutions for different values of $ n $. These solutions contain both non-stationary configurations of the travelling wave type and stationary ones, in particular, depending on one radial variable.