Given an integer array `nums`

, return *the number of all the arithmetic subsequences of*

`nums`

.A sequence of numbers is called arithmetic if it consists of **at least three elements** and if the difference between any two consecutive elements is the same.

- For example,
`[1, 3, 5, 7, 9]`

,`[7, 7, 7, 7]`

, and`[3, -1, -5, -9]`

are arithmetic sequences. - For example,
`[1, 1, 2, 5, 7]`

is not an arithmetic sequence.

A **subsequence** of an array is a sequence that can be formed by removing some elements (possibly none) of the array.

- For example,
`[2,5,10]`

is a subsequence of`[1,2,1,`

.,4,1,__2__,**5**]**10**

The answer is guaranteed to fit in **32-bit** integer.

**Example 1:**

Input:nums = [2,4,6,8,10]Output:7Explanation:All arithmetic subsequence slices are: [2,4,6] [4,6,8] [6,8,10] [2,4,6,8] [4,6,8,10] [2,4,6,8,10] [2,6,10]

**Example 2:**

Input:nums = [7,7,7,7,7]Output:16Explanation:Any subsequence of this array is arithmetic.

**Constraints:**

`1 <= nums.length <= 1000`

`-2`

^{31}<= nums[i] <= 2^{31}- 1

class Solution {
public int numberOfArithmeticSlices(int[] nums) {
}
}