#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1000000007;
int maina() {
  int T;
  cin >> T;
  for (int _t = 0; _t < T; _t++) {
  }
  return 0;
}
int main() {
  ios::sync_with_stdio(false);
  long long N;
  cin >> N;
  vector<long long> in(N);
  for (int i = 0; i < N; ++i) {
    cin >> in[i];
    in[i]--;
  }
  vector<long long> cnt(N);
  cnt[0] = 2;
  long long result = 2;
  for (int i = 1; i < N; ++i) {
    long long total = 2;
    for (int j = in[i]; j < i; ++j) {
      total += cnt[j];
      total %= MOD;
    }
    cnt[i] = total;
    result += total;
    result %= MOD;
  }
  cout << result;
  return 0;
}
