#include <stdio.h>
typedef long long ll;
const int N = 1e7, mod = 1e9 + 7;
int cnt[N + 7];
ll fac[N + 7], inv[N + 7];
inline void init(int n){
	fac[0] = 1;
	for (register int i = 1; i <= n; i++){
		fac[i] = fac[i - 1] * i % mod;
	}
	inv[0] = inv[1] = 1;
	for (register int i = 2; i <= n; i++){
		inv[i] = mod - (mod / i) * inv[mod % i] % mod;
	}
}
inline int read(){
	int ans = 0;
	char ch = getchar();
	while (ch < '0' || ch > '9'){
		ch = getchar();
	}
	while (ch >= '0' && ch <= '9'){
		ans = ans * 10 + (ch ^ 48);
		ch = getchar();
	}
	return ans;
}
int main(){
	int n = read(), ni = n + 1;
	ll ans = 0;
	init(ni);
	for (register int i = 1; i <= n; i++){
		int a = read();
		cnt[a]++;
	}
	for (register int i = 1; i <= N; i++){
		if (cnt[i]>0) ans = (ans + inv[cnt[i] + 1]) % mod;
	}
	printf("%lld", ans*fac[ni]%mod);
	return 0;
}