#include<bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using mint = modint1000000007;
using ll = long long;
using vi = vector<int>;
using vs = vector<string>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
#define rep(i,j,n) for(ll i=j;i<n;i++)
#define rp(i,n) rep(i,0,n)
#define all(v) v.begin(), v.end()
#define pb push_back
#define yes {cout<<"Yes"; return 0;}
#define no {cout<<"No"; return 0;}
#define yn(jg){if(jg) yes; no;}
#define Noo {cout<<-1; return 0;}
#define NL {cout<<endl;}
ll mod0 = 998244353;
ll lmax = 9e18;
ll inf = 2e9;//2147483647
double pi = 3.14159265358979;
//cout<<setprecision(15)<<fixed<<
#define aout(a) {for(auto I:a) cout<<I<<" ";cout<<endl;}
#define bout(a) {for(auto J:a) aout(J);cout<<endl;}
int main() {
	int n;
	cin >> n;
	if (n == 1) {
		cout << 1; return 0;
	}
	mint kosu = 0;
	vll a(n); rp(i, n) {
		cin >> a[i]; kosu += a[i];
	}
	mint sr = 0;
	rp(i, n) {
		sr+= a[i] * (a[i] - 1);
	}
	mint x =kosu;
	mint y = (kosu - 1) * sr;
	y/= (kosu * (kosu - 1));
	x -= y;
	cout << x.val();


}