pstree visually merges identical branches by putting them in square brackets and prefixing them with the repetition count, e.g.

           init-+-getty
                |-getty
                |-getty
                `-getty

       becomes

           init---4*[getty]

       Child threads of a process are found under the parent process and are shown with the process name in curly braces, e.g.

           icecast2---13*[{icecast2}]