von Neumann integer

A finite von Neumann ordinal.

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?]