#include <bits/stdc++.h>
using namespace std;
#define V vector
#define all0(x) (x).begin(),(x).end()
#define all1(x) (x).begin()+1,(x).end()
#define pb push_back
#define fi first
#define se second
#define lb lower_bound
#define ub upper_bound
#define cin std::cin
#define cout std::cout
typedef long long LL;
typedef pair<int, int> pi;
typedef pair<LL, LL> pl;

//const int MN = 2e5 + 20;
const int INF = 2e9 + 1000;//INF
const LL INFLL = 8e18 + 1000;//INF long long 
mt19937 mrand(chrono::steady_clock().now().time_since_epoch().count());
const int mod = 1e9 + 7;
LL MOD(LL x) {
    if(x >= mod) return x - mod;
    if(x < 0) return x + mod;
    return x;
}
LL mul(int a, int b) {
    return 1LL * a * b % mod;
}
//模板区域~~~~~~~

//模板结束~~~~~~~

void solve() {
    int n; cin >> n;
    V<int> a(n + 2);
    V<LL> pow2(n + 1);
    pow2[0] = 1;
    for(int i = 1; i <= n; i++) pow2[i] = MOD(pow2[i - 1] + pow2[i - 1]);
    for(int i = 1; i <= n;i++) cin >> a[i];
    a[n + 1] = INF;
    V<V<V<LL>>> dp(n + 2, V<V<LL>>(56, V<LL>(56)));
    V<V<V<LL>>> cnt(n + 2, V<V<LL>>(56, V<LL>(56)));
    cnt[1][0][0] = 1;

    for(int i = 1; i <= n; i++) {
        for(int p = 0; p <= 55; p++) {
            for(int p2 = 0; p2 <= 55; p2++) {
                //0
                int n_p = p ? p + a[i + 1] - a[i] : 0, n_p2 = p2 ? p2 + a[i + 1] - a[i] : 0;
                if(i == n || n_p >= 56) n_p = 0;
                if(i == n || n_p2 >= 56) n_p2 = 0;
                // if(dp[i][p][p2] && i == n) cout << "HI" << " " << n_p << " " << n_p2 << endl;
                dp[i + 1][n_p][n_p2] = MOD(dp[i + 1][n_p][n_p2] + dp[i][p][p2]);
                cnt[i + 1][n_p][n_p2] = MOD(cnt[i + 1][n_p][n_p2] + cnt[i][p][p2]);
                //1
                dp[i][p][p2] = MOD(dp[i][p][p2] + mul(cnt[i][p][p2], 2));
                if(p2) {
                    int to = a[i] - p2 + 75;
                    to = lb(all1(a), to) - a.begin();
                    dp[to][0][0] = MOD(dp[to][0][0] + mul(dp[i][p][p2], pow2[to - i - 1]));
                    cnt[to][0][0] = MOD(cnt[to][0][0] + mul(cnt[i][p][p2], pow2[to - i - 1]));
                    
                } else {
                    int to = a[i] + 20;
                    to = lb(all1(a), to) - a.begin();
                    int n_p = p ? p + a[to] - a[i] : 0, n_p2 = p2 ? p2 + a[to] - a[i] : 0;
                    n_p2 = n_p, n_p = a[to] - a[i];
                    if(to == n + 1 || n_p >= 56) n_p = 0;
                    if(to == n + 1 || n_p2 >= 56) n_p2 = 0;

                    // if(dp[i][p][p2]) cout << "at : " << i << "to : " << to << " " << n_p << " " << n_p2 << endl
                    //     , cout << dp[i][p][p2] * pow2[to - i] << endl;
                    dp[to][n_p][n_p2] = MOD(dp[to][n_p][n_p2] + mul(dp[i][p][p2], pow2[to - i - 1]));
                    cnt[to][n_p][n_p2] = MOD(cnt[to][n_p][n_p2] + mul(cnt[i][p][p2], pow2[to - i - 1]));
                }
            }
        }
    }

    cout << dp[n + 1][0][0] << endl;
}

int32_t main() {
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    int t=1;
    //cin >> t;
    while (t--) 
    solve();
}