#include<bits/stdc++.h>

using namespace std;
typedef long long ll;

const ll N = 1000 + 5, M = 50 + 5, Mod = 1e9 + 7;

inline ll power(ll x, ll y){
	ll ret = 1;
	while(y){
		if(y & 1) ret = ret * x % Mod;
		x = x * x % Mod, y >>= 1;
	}
	return ret;
}

inline ll inv(ll x){
	return power(x, Mod - 2);
}

ll n = 0, m = 0, c[M] = {}, binom[N][N] = {}, h[N] = {}, f[M] = {}, g[M][N] = {}, ans = 0;

inline ll calc(ll k){
	ll r = 0;
	for(ll i = 0 ; i <= n ; i ++) if(i <= k){
		ll z = binom[n][i] * power(k - i, n) % Mod;
		if(i & 1) r = (r + Mod - z) % Mod; else r = (r + z) % Mod;
	}
	for(ll i = 1 ; i <= n ; i ++) r = r * inv(i) % Mod;
	return r;
}

int main(){
	scanf("%lld", &n);
	for(ll i = 1, x = 0 ; i <= n ; i ++){
		scanf("%lld", &x), x ++;
		c[x] ++, m = max(m, x);
	}
	for(ll i = 0 ; i <= n ; i ++){
		binom[i][0] = 1;
		for(ll j = 1 ; j <= i ; j ++) binom[i][j] = (binom[i - 1][j - 1] + binom[i - 1][j]) % Mod;
	}
	
	h[0] = 1;
	for(ll i = 1 ; i <= n ; i ++) h[i] = h[i - 1] * inv(2) % Mod;
	f[m] = 1;
	for(ll x = m, k = 0 ; x >= 1 ; x --){
		f[x - 1] = (f[x - 1] + f[x] * h[k]) % Mod, g[x - 1][1] = (g[x - 1][1] + f[x - 1] * c[x]) % Mod;
		for(ll i = 1 ; i <= n ; i ++) for(ll j = 0 ; j <= k ; j ++) if(j < 2 * i){
			ll w = binom[k][j] * h[k] % Mod;
			if(2 * i - j <= n) g[x - 1][2 * i - j] = (g[x - 1][2 * i - j] + g[x][i] * w) % Mod;
			else ans = (ans + g[x][i] * w) % Mod;
		}
		k += c[x];
	}
	for(ll i = 1 ; i <= n ; i ++) ans = (ans + g[0][i] * calc(i)) % Mod;
	ans = (Mod + 1 - ans) % Mod;
	printf("%lld", ans);
	return 0;
}