Find possible parenthesizing

Given an input n write a program to generate all possible parenthesizing.

For ex: if n=3, then following is the result

((()))
(())()
()()()
(()())
()(())

Number of such elements is represented as Catalan Number. For more details, see http://en.wikipedia.org/wiki/Catalan_number

A similar problem asks to find all possible permutations of given elements with following two variations:

1. There might be repetitions
2. All elements are unique