#include <bits/stdc++.h>

using namespace std;

const int MAX_N = 40 + 5;
const int MAX_N2 = 800 + 5;
const int P = 1000000007;

int N, M, w[MAX_N];
int pm[MAX_N2][MAX_N2];

struct State {
    int m, cnt[MAX_N];
    State() {
        clear();
    }
    void clear() {
        m = 0;
        for (int i = 1; i <= N; i ++) cnt[i] = 0;
    }
    inline bool operator < (const State &b) const {
        if (m != b.m) {
            return m < b.m;
        }
        for (int i = 1; i <= N; i ++) {
            if (cnt[i] != b.cnt[i]) {
                return cnt[i] < b.cnt[i];
            }
        }
        return false;
    }
    inline bool operator == (const State &b) const {
        if (m != b.m) {
            return false;
        }
        for (int i = 1; i <= N; i ++) {
            if (cnt[i] != b.cnt[i]) {
                return false;
            }
        }
        return true;
    }
};

int main() {
    scanf("%d", &N);
    M = N * (N - 1) >> 1;
    for (int i = 1; i < N; i ++) {
        scanf("%d", &w[i]);
    }
    w[N] = M + 1;
    for (int i = 0; i <= M; i ++) {
        pm[i][0] = 1;
        for (int j = 1; j <= i; j ++) {
            pm[i][j] = 1ll * pm[i][j - 1] * (i - j + 1) % P;
        }
    }
    map<State, int> f;
    queue<State> q;
    State s, ss;
    s.m = 1, s.cnt[1] = N;
    f[s] = 1, q.push(s);
    while (!q.empty()) {
        s = q.front();
        q.pop();
        int fs = f[s];
        f.erase(s);
        int e = 0;
        for (int i = 1; i <= N; i ++) {
            e += (i * (i - 1) >> 1) * s.cnt[i];
        }
        e -= w[s.m] - 1;
        if (e < 0) continue;
        if (s.m == N) {
            printf("%d\n", fs);
            break;
        }
        for (int i = 1; i <= N; i ++) {
            if (!s.cnt[i]) continue;
            for (int j = i + (s.cnt[i] == 1); j <= N; j ++) {
                if (!s.cnt[j]) continue;
                int tk = i * j * (i == j ? s.cnt[i] * (s.cnt[i] - 1) >> 1 : s.cnt[i] * s.cnt[j]);
                int tp = pm[e + i * j - 1][w[s.m + 1] - w[s.m] - 1];
                int tf = 1ll * fs * tk % P * tp % P;
                ss = s;
                ss.cnt[i] --;
                ss.cnt[j] --;
                ss.cnt[i + j] ++;
                ss.m ++;
                if (!f.count(ss)) {
                    f[ss] = 0;
                    q.push(ss);
                }
                int &fss = f[ss];
                fss += tf, fss -= fss >= P ? P : 0;
            }
        }
    }
    return 0;
}