#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

template<typename T>
struct Matrix {
  int h, w;
  vector<vector<T>> d;
  Matrix() {}
  //初期化のときは Matrix<> a(h, w)
  Matrix(int h, int w, T val=0): h(h), w(w), d(h, vector<T>(w,val)) {}
  Matrix& unit() {
    assert(h == w);
    rep(i,h) d[i][i] = 1;
    return *this;
  }
  const vector<T>& operator[](int i) const { return d[i];}
  vector<T>& operator[](int i) { return d[i];}
  Matrix operator*(const Matrix& a) const {
    assert(w == a.h);
    Matrix r(h, a.w);
    rep(i,h)rep(k,w)rep(j,a.w) {
      r[i][j] += d[i][k]*a[k][j];
    }
    return r;
  }
  //Matcix<> newa = a.pow(k)と使う
  Matrix pow(long long t) const {
    assert(h == w);
    if (!t) return Matrix(h,h).unit();
    if (t == 1) return *this;
    Matrix r = pow(t>>1);
    r = r*r;
    if (t&1) r = r*(*this);
    return r;
  }
};

int main()
{
    int t;
    cin >> t;
    rep(_,t){
        ll n, m;
        cin >> n >> m;
        if(n==2){
            Matrix<mint> M(2,2);
            M[0][0] = 1;
            M[0][1] = 1;
            M[1][0] = 2;
            M[1][1] = 1;
            Matrix<mint> res = M.pow(m);
            cout << (res[0][0]+res[1][0]).val() << endl;
            continue;
        }
        Matrix<mint> M(3,3);
        M[0][0] = 1;
        M[0][1] = 1;
        M[0][2] = 1;
        M[1][0] = n;
        M[2][0] = n*(n-1)/2 - n;
        M[1][1] = n-1;
        M[2][1] = n*(n-1)/2 - n - (n-1) + 2;
        M[1][2] = n-2;
        M[2][2] = n*(n-1)/2 - n - 2*(n-1) + 4 +1;
        Matrix<mint> res = M.pow(m);
        mint ans = 0;
        rep(i,3) ans += res[i][0];
        cout << ans.val() << endl;
    }

    return 0;
}