#include <bits/stdc++.h>

using namespace std;

const int md = 1000000007;

inline void add(int &a, int b) {
  a += b;
  if (a >= md) {
    a -= md;
  }
}

inline int mul(int a, int b) {
  return (long long) a * b % md;
}

inline int power(int a, int b) {
  int res = 1;
  while (b > 0) {
    if (b & 1) {
      res = mul(res, a);
    }
    b >>= 1;
    a = mul(a, a);
  }
  return res;
}

inline int inv(int x) {
  return power(x, md - 2);
}

const int N = 2222;

int a[N];
int dp[N][N], sum[N][N];

int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    scanf("%d", a + i);
  }
  for (int i = 0; i <= n; i++) {
    for (int j = 0; j <= i; j++) {
      sum[i][j] = 0;
    }
  }
  sum[0][0] = 1;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j <= i; j++) {
      add(sum[i + 1][j], sum[i][j]);
      add(sum[i + 1][j + 1], mul(sum[i][j], a[i]));
    }
  }
  dp[1][1] = 1;
  for (int i = 2; i <= n; i++) {
    for (int j = 1; j <= i; j++) {
      dp[i][j] = 0;
      add(dp[i][j], mul(dp[i - 1][j - 1], j * (j - 1) / 2));
      add(dp[i][j], mul(dp[i - 1][j], j * (i - j) + (i - j) * (i - j - 1)));
    }
  }
  int ans = 0;
  for (int j = 1; j <= n; j++) {
    add(ans, mul(sum[n][j], dp[n][j]));
  }
  int ways = 1;
  while (n >= 2) {
    ways = mul(ways, mul(n, n - 1));
    n--;
  }
  printf("%d\n", mul(ans, inv(ways)));
  return 0;
}