#include<bits/stdc++.h> #include<atcoder/all> #define rep(i,n) for(int i=0;i<n;i++) using namespace std; using namespace atcoder; typedef long long ll; typedef vector<int> vi; typedef vector<long long> vl; typedef vector<vector<int>> vvi; typedef vector<vector<long long>> vvl; typedef long double ld; typedef pair<int, int> P; ostream& operator<<(ostream& os, const modint& a) {os << a.val(); return os;} template <int m> ostream& operator<<(ostream& os, const static_modint<m>& a) {os << a.val(); return os;} template<typename T> istream& operator>>(istream& is, vector<T>& v){int n = v.size(); assert(n > 0); rep(i, n) is >> v[i]; return is;} template<typename U, typename T> ostream& operator<<(ostream& os, const pair<U, T>& p){os << p.first << ' ' << p.second << "\n"; return os;} template<typename T> ostream& operator<<(ostream& os, const vector<T>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : " "); return os;} template <typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : ""); return os;} using mint = modint998244353; void solve(){ int n, m; cin >> n >> m; auto c2 = [&](int k){ if(k <= 3) return (mint)0; return (mint)k * (k - 3) / 2; }; vector<mint> dp(3); dp[0] = 1; dp[1] = n; dp[2] = c2(n); rep(i, m - 1){ vector<mint> dp_old(3); swap(dp, dp_old); dp[0] = dp_old[0] + dp_old[1] + dp_old[2]; dp[1] = dp_old[0] * n + dp_old[1] * (n - 1) + dp_old[2] * (n - 2); dp[2] += dp_old[0] * c2(n); dp[2] += dp_old[1] * ((mint)(n - 1) * (n - 2) / 2 - (n - 2)); if(n >= 4) dp[2] += dp_old[2] * ((mint)(n - 2) * (n - 3) / 2 - (n - 4)); } mint ans = dp[0] + dp[1] + dp[2]; cout << ans << "\n"; } int main(){ int t; cin >> t; rep(i, t) solve(); return 0; }