Kata

We have a set of consecutive numbers from 1 to n. We want to count all the subsets that do not contain consecutive numbers. E.g.

If our set S1 is equal to [1,2,3,4,5] The subsets that fulfill these property are:

[1],[2],[3],[4],[5],[1,3],[1,4],[1,5],[2,4],[2,5],[3,5],[1,3,5]

A total of 12 subsets.

From the set S2 equals to[1,2,3], it is obvious that we have only 4 subsets and are:

[1],[2],[3],[1,3]

Make a code that may give the amount of all these subsets for any integer n >= 2 .

Features of the random tests:

number of tests = 100 
10 <= n <= 120