#include <iostream>
#include <vector>
using namespace std;
 
const int MAX_VAL = 1e6;  // Maximum possible value of elements in the array
 
// Function to calculate sum of GCD over all pairs
long long gcd_sum_over_pairs(const vector<int>& arr) {
    // Step 1: Create a frequency array
    vector<int> freq(MAX_VAL + 1, 0);
    for (int num : arr) {
        freq[num]++;
    }
 
    long long result = 0;
 
    // Step 2: For each gcd value `g`, calculate how many multiples of `g` exist
    for (int g = 1; g <= MAX_VAL; g++) {
        // Count multiples of g
        long long count_g = 0;
        for (int multiple = g; multiple <= MAX_VAL; multiple += g) {
            count_g += freq[multiple];
        }
 
        // If there are at least 2 numbers with GCD `g`, calculate the number of pairs
        if (count_g >= 2) {
            long long pairs_g = count_g * (count_g - 1) / 2;  // Combinatorial formula nC2
            result += g * pairs_g;  // Add contribution of these pairs to the result
        }
    }
 
    return result;
}
 
int main() {
    int n;
    cin >> n;
    vector<int> arr;
    int x;
    for(int i = 0; i < n; ++i){
    	cin >> x;
    	arr.push_back(x);
    }
    cout << gcd_sum_over_pairs(arr) << endl;
 
    return 0;
}
 

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