Show that the given set has a cardinality of ℵ0 by establishing a one-to-one correspondence between the elements of the given set and the elements of N.
1, 1/3, 1/9, 1/27, , 1/3n − 1,
Let N = 1, 2, 3, , n, .
Then a one-to-one correspondence between the given set and the set of natural numbers N is given by the following general correspondence.