#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<vector>
#include<set>
#include<map>

using namespace std;

#define x first
#define y second
#define NMAX 1000004
#define MOD 1000000007

int n, v[NMAX], f[NMAX];
int fact[NMAX], inv[NMAX];

int rid_log(int a, int b){
    if(!b)
        return 1;
    int a2 = rid_log(a, b / 2);
    if(b&1)
        return (long long)a2 * a2 % MOD * a % MOD;
    return (long long)a2 * a2 % MOD;
}

inline int combinari(int n, int k){
    return (long long)fact[n] * inv[k] % MOD * inv[n - k] % MOD;
}

int main (){
    
    scanf("%d",&n);
    fact[0] = 1;
    for(int i = 1; i <= n; i++)
        fact[i] = ((long long)fact[i - 1] * i) % MOD;
    for(int i = 0; i <= n; i++)
        inv[i] =  rid_log(fact[i], MOD - 2);
    int vmax = 0;
    for(int i = 1; i <= n; i++){
        scanf("%d",&v[i]);
        f[v[i]]++;
        vmax = max(vmax, v[i]);
    }
    
    int ans = 1;
    for(int i = 1; i <= vmax; i++){
        int ans2 = 0;
        for(int j = 0; j <= f[i]; j++){
            int comb = combinari(f[i], j);
            ans2 += (long long) comb * comb % MOD;
            if(ans2 >= MOD)
                ans2 -= MOD;
        }
        ans = (long long)ans * ans2 % MOD;
    }
    
    ans--;
    if(ans < 0)
        ans += MOD;
    printf("%d\n", ans);
    
    return 0;
}