You are given `nums`, an array of positive integers of size `2 * n`. You must perform `n` operations on this array.

In the `ith` operation (1-indexed), you will:

- Choose two elements, `x` and `y`.
- Receive a score of `i * gcd(x, y)`.
- Remove `x` and `y` from `nums`.

Return the maximum score you can receive after performing `n` operations.

The function `gcd(x, y)` is the greatest common divisor of `x` and `y`.

Example 1:

    Input: nums = [1,2]
    Output: 1
    Explanation: The optimal choice of operations is:
    (1 * gcd(1, 2)) = 1

Example 2:

    Input: nums = [3,4,6,8]
    Output: 11
    Explanation: The optimal choice of operations is:
    (1 * gcd(3, 6)) + (2 * gcd(4, 8)) = 3 + 8 = 11

Example 3:

    Input: nums = [1,2,3,4,5,6]
    Output: 14
    Explanation: The optimal choice of operations is:
    (1 * gcd(1, 5)) + (2 * gcd(2, 4)) + (3 * gcd(3, 6)) = 1 + 4 + 9 = 14

Constraints:

- `1 <= n <= 7`
- `nums.length == 2 * n`
- `1 <= nums[i] <= 106`