Count Divisible Permutations

SDE-1

Suppose you have n integers from 1 through n. A permutation of those n integers is considered a Divisible Permutation if for every i, where 1 <= i <= n, either of the following is true:

• perm[i] is divisible by i.
• i is divisible by perm[i].

Given an integer n, find the total number of the valid Divisible Permutations.

Note - you may want to refer to LC 810