Plant The Plants

Chef’s has been asked to find the no of ways he can arrange the n(n>= 3) plants in a line left to right, so that he cannot find any three plants that are arranged tallest to shortest (in left to right order). The plant’s height triples do not have to be adjacent. The height of the n plants are in order {1, 2, 3, …, n-1, n} ###Input: The first line contains a single integer n which denotes t