2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/226700We show that the number of quivers in the mutation class of a quiver of Dynkin type $D_n$ is given by $\sum_{d|n} ϕ(n/d)\binom{2d}{d}/(2n)$ for $n \geq 5$. To obtain this formula, we give a correspondence between the quivers in the mutation class and certain rooted trees.20 pages,minor changes, grammatical corrections and layoutRepresentation TheoryCombinatoricstext