#include <bits/stdc++.h>
#define int long long
using namespace std;

const int N = 1010, M = 80, mod = 1e9 + 7;
int n, ans, a[N], pw[N], f[N][M][M];
void add(int &x, int y) {x = (x + y) % mod; }
int work(int x, int y) {
	return (!x || x + y > 75) ? 0 : x + y;
}

signed main() {
	cin >> n;
	pw[0] = 1;
	for (int i=1; i<=n; ++i) pw[i] = pw[i - 1] * 2 % mod;
	for (int i=1; i<=n; ++i) cin >> a[i];
	a[0] = a[1] - 1;
	f[0][0][0] = 1;
	for (int i=0; i<n; ++i)
		for (int j=0; j<=75; ++j) {
			int nxt = a[i + 1] + 19;
			if (j && nxt < a[i] - j + 75) nxt = a[i] - j + 75;
			nxt = upper_bound(a + 1, a + n + 1, nxt) - a - 1;
			for (int k=0; k<=75; ++k) if (f[i][k][j]) {
				//printf("%d %d %d  %d  nxt %d\n", i, k, j, f[i][k][j], nxt);
				add(f[i + 1][work(k, a[i + 1] - a[i])][work(j, a[i + 1] - a[i])], f[i][k][j]);
				add(f[nxt][a[nxt] - a[i] > 75 ? 0 : a[nxt] - a[i]][work(k, a[nxt] - a[i])], f[i][k][j] * pw[nxt - i - 1]);
				add(ans, f[i][k][j] * pw[n - i - 1]);
				
				/*add(f[nxt][work(k, nxt - i)][work(j, nxt - i)], f[i][k][j]);
				add(f[nxt][nxt - i][work(k, nxt - i)], f[i][k][j] * (pw[nxt - i] - 1));
				add(ans, f[i][k][j] * (pw[nxt - i] - 1) % mod * pw[n - nxt]);*/
			}
		}
	cout << ans * 2 % mod << "\n";
	return 0;
}