import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		String[] sa = br.readLine().split(" ");
		int[] a = new int[n];
		for (int i = 0; i < n; i++) {
			a[i] = Integer.parseInt(sa[i]);
		}
		br.close();

		int mod = 1000000007;
		int rn = (int) Math.sqrt(n) - 2;
		if (rn < 2) {
			rn = 2;
		}
		long[][] dp = new long[rn][n + 2];
		dp[0][0] = 1;
		for (int i = 0; i < n; i++) {
			for (int j = 1; j < rn; j++) {
				int p = i - j;
				if (p < 0) {
					break;
				}
				dp[j][i] += dp[j][p];
				dp[j][i] %= mod;
			}
			for (int j = 1; j < rn; j++) {
				dp[0][i] += dp[j][i];
			}
			dp[0][i] %= mod;

			dp[0][i + 1] += dp[0][i];
			if (a[i] == 1) {
				dp[1][i + 2] += dp[0][i];
			} else if (a[i] < rn) {
				int c = i + a[i];
				if (c < n) {
					dp[a[i]][c] += dp[0][i];
				}
			} else {
				for (int j = i + a[i]; j < n; j += a[i]) {
					dp[0][j] += dp[0][i];
				}
			}
		}
		System.out.println(dp[0][n - 1]);
	}
}