An n-tuple (x1,...,xn) is an ordered list of n sets. It can be constructed in several ways. A popular definition is the original set x1 for n=1 and the ordered pair ((x1,...,xn-1),xn) otherwise.
Klick on the ordered pair ( 351, 39 ) or the natural number 88 to see how it may be defined as a set.
(351, 39, 88) = ( ( 351, 39 ), 88 )