#include <bits/stdc++.h>
using namespace std;
#define int long long
const int mod = 1e9 + 7;
const int N = 608;
int bm(int b, int p) {
if (!p) return 1;
int res = bm(b, p / 2);
res = res * res % mod;
if (p % 2 == 1) res = res * b % mod;
return res;
}
int n, f[N << 1][N], fac[N], ifac[N], a[N << 1], sf[N << 1], g[N], fib[N][N];
int ncr(int x, int y) {
if (x < y || x < 0 || y < 0) return 0;
return fac[x] * ifac[y] % mod * ifac[x - y] % mod;
}
int32_t main() {
ios::sync_with_stdio(0); cin.tie(0);
cin >> n;
fac[0] = ifac[0] = 1;
for (int i = 1; i <= n; i++) {
fac[i] = fac[i - 1] * i % mod;
ifac[i] = bm(fac[i], mod - 2);
}
for (int i = 1; i <= n; i++) {
int val;
cin >> val;
a[val] = 1;
}
for (int i = 2 * n; i >= 1; i--) sf[i] = sf[i + 1] + a[i];
int inv = bm(2, mod - 2);
g[0] = 1;
for (int i = 1; i <= n; i++) for (int j = 1; j <= i; j++) g[i] += g[j - 1] * g[i - j] % mod * ncr(i - 1, j - 1) % mod * (i - j + 2) % mod;
if (!a[2 * n]) return cout << "0\n", 0;
f[2 * n + 1][0] = 1;
for (int i = 2 * n; i >= 1; i--) {
for (int j = 0; j <= n; j++) {
if (a[i]) {
f[i][j] = f[i + 1][j];
for (int k = 0; k < j; k++) (f[i][j] += f[i + 1][k] * g[j - k - 1] % mod * (j - k + 1) % mod * ncr(sf[i + 1] - k, j - k - 1) % mod) %= mod;
} else {
int num_dead = (2 * n - i) - sf[i + 1];
// cout << num_dead << '\n';
if (j > num_dead) f[i][j] = f[i + 1][j] * ((j - num_dead + mod) % mod) % mod;
}
// cout << "dp @ " << i << " " << j << " = " << f[i][j] << "\n";
}
}
cout << f[1][n] * bm(inv, n) % mod << '\n';
}
