  In this article we prove explicit formulae for the number of non-isomorphic
cluster-tilted algebras of type \tilde{A}_n in the derived equivalence classes.
In particular, we obtain the number of elements in the mutation classes of
quivers of type \tilde{A}_n. As a by-product, this provides an alternative
proof for the number of quivers of Dynkin type D_n which was first determined
by Buan and Torkildsen.
