Counting Rooted Trees: The Universal Law t(n)~C ρ-n n-3/2

Combinatorial classes T that are recursively defined using combinations of the standard multiset, sequence, directed cycle and cycle constructions, and their restrictions, have generating series T(z) with a positive radius of convergence; for most of these a simple test can be used to quickly show that the form of the asymptotics is the same as that for the class of rooted trees: Cρn , where ρ is the radius of convergence of T.