See Random deterministic automata
ON THE NUMBER OF DISTINCT LANGUAGES ACCEPTED BY FINITE AUTOMATA WITH n STATES
EnumerationofAutomata,Languages,and Regular Expressions
The state complexity of random DFAs
On the average state and transition complexity of finite languages
REGAL: A Library to Randomly and Exhaustively Generate Automata in C++ !
Distribution of the number of accessible states in a random deterministic automaton
Enumerating Finitary Processes
Sampling different kinds of acyclic automata using Markov chains
Random walk on sparse random digraphs
A Hitchhiker's Guide to descriptional complexity through analytic combinatorics
A Survey on Operational State Complexity
An Introduction to Descriptional Complexity of Regular Languages through Analytic Combinatorics
Mixing times of random walks on dynamic configuration models