#include <bits/stdc++.h>
#define inf INT_MAX
#define NN INT_MIN
typedef long long ll;
using namespace std;
#define int ll
int n;
ll a[200015];
ll fac[2000015], infac[2000015];
ll bigger[200015], smll[200015], eql[200015];
const ll mod = 1e9 + 7;
bool vis1[200015];
struct node
{
	ll data, i;
	bool operator<(const node &t) const
	{
		return data < t.data;
	}
} b[200015];
ll qpow(ll a, ll n)
{
	ll ans = 1;
	while (n)
	{
		if (n & 1)
			ans = (ans * a) % mod;
		a = (a * a) % mod;
		n >>= 1;
	}
	return ans % mod;
}
ll femat(ll x)
{
	return qpow(x, mod - 2);
}
void init()
{
	fac[0] = 1;
	for (int i = 1; i <= 200030; i++)
		fac[i] = fac[i - 1] * i % mod;
	for (int i = 0; i <= 200030; i++)
		infac[i] = femat(fac[i]) % mod;
}
ll C(int n, int m)
{
	if (n == 0 || m == 0)
		return 1;
	return fac[n] * infac[m] % mod * infac[n - m] % mod;
}
signed main()
{
#ifdef WHX_AK_IOI
	freopen("data.in", "r", stdin);
// freopen("dataout.txt","w",stdout);
#endif
	ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
	cin >> n;
	init();
	for (int i = 1; i <= n; i++)
	{
		cin >> a[i];
		b[i].data = a[i];
		b[i].i = i;
	}
	// cout << infac[7000] << endl;
	sort(b + 1, b + n + 1);
	for (int i = 1; i <= n; i++)
	{
		smll[b[i].i] = i - 1;
		bigger[b[i].i] = n - i;
		while (b[i].data == b[i + 1].data)
			i++, smll[b[i].i] = smll[b[i - 1].i], bigger[b[i].i] = bigger[b[i - 1].i];
	}
	// for (int i = 1; i <= n; i++)
	// 	cout << smll[i] << endl;
	for (int i = 1; i <= n; i++)
		while (b[i].data == b[i + 1].data)
			i++, eql[b[i].i] = eql[b[i - 1].i] + 1;
	// for (int i = 1; i <= n; i++)
	// 	cout << eql[b[i].i] << endl;
	for (int i = 1; i <= n; i++)
	{
		int j = i;
		while (eql[b[i + 1].i] > eql[b[i].i])
			i++;
		for (int k = j; k <= i; k++)
			eql[b[k].i] = eql[b[i].i];
	}
	// for (int i = 1; i <= n; i++)
	// 	cout << eql[b[i].i] << endl;
	// for (int i = 1; i <= n; i++)
	// 	cout << bigger[b[i].i] << endl;
	// for (int i = 1; i <= n; i++)
	// 	bigger[i] -= eql[i];
	// for (int i = 1; i <= n; i++)
	// 	cout << smll[i] << ' ';
	// cout << endl;
	// for (int i = 1; i <= n; i++)
	// 	cout << eql[i] << ' ';
	// cout << endl;
	// for (int i = 1; i <= n; i++)
	// 	cout << bigger[i] << ' ';
	// cout << endl;
	ll ans = 0;
	for (int i = 1; i <= n; i++)
	{
		if (vis1[a[i]] == 1)
			continue;
		vis1[a[i]] = 1;
		if (eql[i] < a[i] - 1 - smll[i])
			continue;
		eql[i] -= max(0LL, a[i] - 1 - smll[i]);
		bigger[i] -= max(0LL, a[i] - 1 - smll[i]);
		if (smll[i] < a[i] - 1)
			smll[i] = a[i] - 1;

		// cout << endl
		// 	 << endl;
		// cout << "case:" << i << endl
		// 	 << "sml:" << smll[i] << endl
		// 	 << "eql:" << eql[i] << endl
		// 	 << "bg:" << bigger[i] << endl
		// 	 << endl;
		ans = (ans + C(smll[i], a[i] - 1) * qpow(2, bigger[i]) % mod) % mod;
		for (int j = 1; j <= eql[i]; j++)
		{
			smll[i]++, bigger[i]--;
			// cout << "case:" << i << endl
			// 	 << "sml:" << smll[i] << endl
			// 	 << "eql:" << eql[i] << endl
			// 	 << "bg:" << bigger[i] << endl
			// 	 << endl;
			ans = (ans + C(smll[i], a[i] - 1) * qpow(2, bigger[i]) % mod) % mod;
		}
	}
	cout << ans << endl;
	// system("pause");
	return 0;
}