Torni

#include <iostream>
constexpr long long mod = 1000000007;
constexpr int max = 1000001;
int z[max];
int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	z[1] = 2;
	z[2] = 8;
	for (int i = 3; i < max; ++i)
		z[i] = ((6ll * z[i - 1] - 7ll * z[i - 2]) % mod + mod) % mod;
	int t;
	std::cin >> t;
	while (t--) {
		int n;
		std::cin >> n;
		std::cout << z[n] << '\n';
	}
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 2, 3

Verdict: ACCEPTED

Test 3

Group: 3

Verdict: ACCEPTED