Input: N = 5
Output : 14
Following are the sub-sequences which are first decreasing and then increasing:
[2, 1, 3, 4, 5], [3, 1, 2, 4, 5], [4, 1, 2, 3, 5], [5, 1, 2, 3, 4],
[3, 2, 1, 4, 5], [4, 2, 1, 3, 5], [5, 2, 1, 3, 4], [4, 3, 1, 2, 5],
[5, 3, 1, 2, 4], [5, 4, 1, 2, 3], [5, 4, 3, 1, 2], [5, 4, 2, 1, 3],
[5, 3, 2, 1, 4], [4, 3, 2, 1, 5]
Input : N = 1
Output : 0