Null controllability for singular cascade systems of \begin{document}$ n $\end{document} -coupled degenerate parabolic equations by one control force

In this paper, we consider a class of cascade systems of \begin{document}$ n $\end{document} -coupled degenerate parabolic equations with singular lower order terms. We assume that both degeneracy and singularity occur in the interior of the space domain and we focus on null controllability problem. To this aim, we prove first Carleman estimates for the associated adjoint problem, then, we infer from it an indirect observability inequality. As a consequence, we deduce null controllability result when a unique distributed control is exerted on the system.