#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
const int C = 26;
void add(int &x, int y) {
  x += y;
  while (x >= MOD) x -= MOD;
  while (x < 0) x += MOD;
}
int fix(int x) {
  while (x >= MOD) x -= MOD;
  while (x < 0) x += MOD;
  return x;
}
int pw(int a, int b) {
  int ret = 1;
  while (b) {
    if (b & 1) ret = 1ll * ret * a % MOD;
    b >>= 1;
    a = 1ll * a * a % MOD;
  }
  return ret;
}
const int MAXN = 1e3 + 10;
int n, dp[MAXN], p[MAXN];
void solve() {
  cin >> n;
  for (int i = 0; i < n; ++i) cin >> p[i], --p[i];
  int ans = 0;
  for (int i = 0; i < n; i++) {
    dp[i] = 1;
    for (int j = p[i]; j < i; j++) add(dp[i], dp[j]);
    add(ans, dp[i]);
  }
  add(ans, ans);
  cout << ans << "\n";
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int te = 1;
  for (int w = 1; w <= te; w++) {
    solve();
  }
  return 0;
}
