using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var t = NN;
        var ans = new long[t];
        for (var u = 0; u < t; ++u)
        {
            var c = NList;
            var (w, h) = (c[0], c[1]);
            ans[u] = Treasure(h, w);
        }
        WriteLine(string.Join("\n", ans));
    }
    static int mod = 998_244_353;
    static int rev2 = 499_122_177;
    static long Treasure(int h, int w)
    {
        var dp = new long[3];
        dp[0] = 1;
        for (var i = 0; i < h; ++i)
        {
            var ndp = new long[3];
            ndp[0] = (dp[0] + dp[1] + dp[2]) % mod;
            if (w == 1)
            {
                ndp[1] = dp[0];
            }
            else if (w == 2)
            {
                ndp[1] = (dp[0] * 2 + dp[1]) % mod;
            }
            else if (w == 3)
            {
                ndp[1] = (dp[0] * 3 + dp[1] * 2) % mod;
            }
            else
            {
                ndp[1] = (dp[0] * w + dp[1] * (w - 1) + dp[2] * (w - 2)) % mod;
                ndp[2] = (dp[0] * ((long)w % mod * (w - 1) % mod * rev2 % mod + mod - w) +
                    dp[1] * ((long)(w - 1) % mod * (w - 2) % mod * rev2 % mod + mod - w + 2) +
                    dp[2] * ((long)(w - 2) % mod * (w - 3) % mod * rev2 % mod + mod - w + 4)) % mod;
            }
            dp = ndp;
        }
        return (dp[0] + dp[1] + dp[2]) % mod;
    }
    class NCR
    {
        int[] facts;
        int[] revFacts;
        int mod;
        public NCR(int n, int mod)
        {
            facts = new int[n + 1];
            revFacts = new int[n + 1];
            this.mod = mod;
            facts[0] = 1;
            var tmp = 1L;
            for (var i = 1; i <= n; ++i)
            {
                tmp = (tmp * i) % mod;
                facts[i] = (int)tmp;
            }
            tmp = Exp(facts[n], mod - 2);
            revFacts[n] = (int)tmp;
            for (var i = n; i > 1; --i)
            {
                tmp = (tmp * i) % mod;
                revFacts[i - 1] = (int)tmp;
            }
            revFacts[0] = 1;
        }
        public long Exp(long n, long k)
        {
            n = n % mod;
            if (k == 0) return 1;
            if (k == 1) return n;
            var half = Exp(n, k / 2);
            var result = (half * half) % mod;
            return ((k % 2) == 0) ? result : ((result * n) % mod);
        }
        public long Calc(int n, int r)
        {
            return (long)facts[n] * revFacts[r] % mod * revFacts[n - r] % mod;
        }
        /// <summary>nが大きくrが小さい場合の計算</summary>
        public long Calc2(int n, int r)
        {
            var tmp = 1L;
            for (var i = 0; i < r; ++i)
            {
                tmp = tmp * (n - i) % mod;
            }
            return tmp * revFacts[r] % mod;
        }
        public long NPR(int n, int r)
        {
            return (long)facts[n] * revFacts[r] % mod;
        }
        public long Fact(int n)
        {
            return facts[n];
        }
        public long RevFact(int n)
        {
            return revFacts[n];
        }
    }
}