Torni

#include <algorithm>
#include <iostream>
#include <vector>

using namespace std;

int main()
{
	int t;
	cin >> t;
	vector<int> ns(t);
	int m = 2;
	for (int i = 0; i < t; ++i) {
		cin >> ns[i];
		m = max(m, ns[i]);
	}
	vector<long> s(m);
	s[0] = 2;
	s[1] = 8;
	for (int i = 2; i < m; ++i) {
		s[i] = (6*s[i-1] - 7*s[i-2]) % 1000000007;
		if (s[i] < 0) s[i] += 1000000007;
	}
	for (auto x : ns) {
		cout << s[x-1] << endl;
	}
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 2, 3

Verdict: ACCEPTED

Test 3

Group: 3

Verdict: ACCEPTED