## von Neumann integer

The von Neumann integer N is a finite set with N elements which are the von Neumann integers 0 to N-1. Thus

0 = {} = {} 1 = {0} = {{}} 2 = {0, 1} = {{}, {{}}} 3 = {0, 1, 2} = {{}, {{}}, {{}, {{}}}} ...

The set of von Neumann integers is infinite, even though each of its elements is finite.

[Origin of name?]