#include <bits/stdc++.h>
using namespace std;
#define ar array
#define sz(v) int(std::size(v))
using i64 = long long;
const int MAXN = 606;
const int MOD = 1e9 + 7;
int N;
bool use[MAXN * 2];
int take[MAXN][MAXN];
int nck[MAXN][MAXN];
int dp[MAXN + 1], ndp[MAXN + 1];
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> N;
for (int i = 0; i < N; i++) {
int x;
cin >> x;
use[x] = 1;
}
take[0][0] = 1;
for (int n = 1; n <= N; n++) for (int k = 0; k <= n; k++) {
i64 x = take[n - 1][k];
if (k >= 1) x += (i64) take[n - 1][k - 1] * 2 * k;
if (k >= 2) x += (i64) take[n - 1][k - 2] * k * (k - 1);
take[n][k] = x % MOD;
}
for (int n = 0; n <= N; n++) {
nck[n][0] = 1;
for (int k = 1; k <= n; k++) {
nck[n][k] = nck[n - 1][k] + nck[n - 1][k - 1];
if (nck[n][k] >= MOD) nck[n][k] -= MOD;
}
}
int cnt_rem = 0, cnt_use = 0;
dp[0] = 1;
for (int i = N * 2; i >= 1; i--) {
fill(ndp, ndp + N + 1, 0);
if (!use[i]) {
for (int j = cnt_rem; j <= cnt_use; j++) if (dp[j])
ndp[j] = (i64) dp[j] * (j - cnt_rem) % MOD;
cnt_rem++;
} else {
for (int j = cnt_rem; j <= cnt_use; j++) if (dp[j]) {
ndp[j] = (ndp[j] + dp[j]) % MOD;
for (int k = 1; j + k <= cnt_use + 1; k++)
ndp[j + k] = (ndp[j + k] + (i64) dp[j] * (k + 1) % MOD * nck[cnt_use - j][k - 1] % MOD * take[k - 1][k - 1]) % MOD;
}
cnt_use++;
}
swap(dp, ndp);
}
i64 ans = dp[N];
for (int i = 0; i < N; i++) ans = ans * (MOD + 1) / 2 % MOD;
cout << ans << '\n';
}
