#include <atcoder/all>
using namespace std;

int main(){
    int N, v;
    cin >> N;
    
    atcoder::modint1000000007 s, s1;
    while(N--){
        cin >> v;
        s1 += s * v;
        s += v;
    }

    cout << (1 + 2 * s1 / s).val() << '\n';
}