// In the name of god
#include <bits/stdc++.h>
#define F first
#define S second
#define pb push_back
#define all(x) x.begin(), x.end()
#define Sort(x) sort(all(x))
#define debug(x) cerr << #x << " : " << x << "\n"
#define usefile freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef string str;
const int maxn = 1e4 + 5;
const ll mod = 1e6 + 7;
const ll inf = 1e18;
int n;
vector <int> dp[maxn];
int ans = 1, num;
ll a[maxn];
bool mrk[maxn];
int main(){
ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
cin >> n;
for(int i = 0; i < n; i ++)cin >> a[i];
dp[0].resize(n + 1);
dp[1].resize(n + 1);
for(int i = 1; i < n; i ++)dp[0][i] = 1;
for(int i = 1; i < n; i ++)dp[1][i] = i + 1;
int m = n - 1;
for(int j = 2; j < n; j ++){
dp[j].resize(m + 2);
for(ll i = 1; i < m; i ++)dp[j][i] = (i * dp[j - 1][i] + dp[j - 1][i + 1]) % mod;
m --;
}
mrk[1] = 1; num = 1;
for(int i = 1; i < n; i ++){
bool bl = 0;
if(!mrk[a[i]]){
mrk[a[i]] = 1;
num ++; bl = 1;
}
if(bl)ans = (ans + ((a[i] - 1ll) * dp[n - i - 1][num - 1] % mod)) % mod;
else ans = (ans + ((a[i] - 1ll) * dp[n - i - 1][num] % mod)) % mod;
}
cout << ans;
}
