using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;
class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var a = NList;
        var sum = a.Sum();
        var mod = 1_000_000_007;
        var revsum = Exp(sum, mod - 2, mod);
        var ans = (long)sum;
        foreach (var ai in a)
        {
            ans = (ans + mod - (long)ai * (ai - 1) % mod * revsum % mod) % mod;
        }
        WriteLine(ans);
    }
    static long Exp(int n, int k, int mod)
    {
        if (k == 0) return 1;
        if (k == 1) return n % mod;
        var half = Exp(n, k / 2, mod);
        var result = (half * half) % mod;
        return ((k % 2) == 0) ? result : ((result * n) % mod);
    }
    static List<int[]> NCRList(int n, int r)
    {
        var res = new List<int[]>();
        _NCRList(n, r, new List<int>(), res);
        return res;
    }
    static void _NCRList(int n, int r, List<int> list, List<int[]> res)
    {
        if (list.Count == r) res.Add(list.ToArray());
        for (var i = list.Count == 0 ? 0 : (list.Last() + 1); i < n; ++i)
        {
            list.Add(i);
            _NCRList(n, r, list, res);
            list.RemoveAt(list.Count - 1);
        }
    }
    class NCR
    {
        int[] facts;
        int[] revFacts;
        int mod;
        public NCR(int n, int mod)
        {
            facts = new int[n + 1];
            revFacts = new int[n + 1];
            this.mod = mod;
            facts[0] = 1;
            var tmp = 1L;
            for (var i = 1; i <= n; ++i)
            {
                tmp = (tmp * i) % mod;
                facts[i] = (int)tmp;
            }
            tmp = Exp(facts[n], mod - 2);
            revFacts[n] = (int)tmp;
            for (var i = n; i > 1; --i)
            {
                tmp = (tmp * i) % mod;
                revFacts[i - 1] = (int)tmp;
            }
            revFacts[0] = 1;
        }
        public long Exp(long n, long k)
        {
            n = n % mod;
            if (k == 0) return 1;
            if (k == 1) return n;
            var half = Exp(n, k / 2);
            var result = (half * half) % mod;
            return ((k % 2) == 0) ? result : ((result * n) % mod);
        }
        public long Calc(int n, int r)
        {
            return (long)facts[n] * revFacts[r] % mod * revFacts[n - r] % mod;
        }
        /// <summary>nが大きくrが小さい場合の計算</summary>
        public long Calc2(int n, int r)
        {
            var tmp = 1L;
            for (var i = 0; i < r; ++i)
            {
                tmp = tmp * (n - i) % mod;
            }
            return tmp * revFacts[r] % mod;
        }
        public long NPR(int n, int r)
        {
            return (long)facts[n] * revFacts[r] % mod;
        }
        public long Fact(int n)
        {
            return facts[n];
        }
        public long RevFact(int n)
        {
            return revFacts[n];
        }
    }
}