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

#include <atcoder/all>
using mint = atcoder::modint998244353;

void solve() {
	long long N, M;
	cin >> M >> N;
	vector<vector<mint>> dp(N+1, vector<mint>(3));
	dp[0][0] = 1;
	for( int i = 1; i <= N; i++ ) {
		dp[i][0] = dp[i-1][0]+dp[i-1][1]+dp[i-1][2];
		dp[i][1] = dp[i-1][0]*M+dp[i-1][1]*(M-1)+dp[i-1][2]*(M-2);
		dp[i][2] = dp[i-1][0]*M*(M-3)/2+dp[i-1][1]*(M-2)*(M-3)/2+dp[i-1][2]*(M*M-7*M+14)/2;
	}
	cout << accumulate(dp[N].begin(), dp[N].end(), mint(0)).val() << endl;
}

int main() {
	int T;
	cin >> T;
	while(T--) { solve(); }
}