#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

ll dp[2500][2500], sum[2500][2500];

ll const md = 1e9 + 7;

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    ll n;
    cin >> n;
    vector <ll> a(n);
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
        dp[i][i] = 1;
    }
    for (int i = 0; i < n; ++i) {
        for (int j = i - 1; j > -1; --j) {
            if (a[i] == a[j]) {
                ll add = 0;
                for (int k = j + 1; k < i; ++k)
                        for (int h = k; h > j; --h)
                             add += dp[h][k], add %= md;
                dp[j][i] += add;
                dp[j][i] %= md;
                dp[j][i]++;
                dp[j][i] %= md;
            }
        }
    }
    ll ans = 0;
    for (int i = 0; i < n; ++i) {
        for (int j = i; j > -1; --j) {
            ans += dp[j][i];
            ans %= md;
        }
    }
    cout << ans << "\n";
    return 0;
}