mod = 998244353
def solve():
  N,M = map(int,input().split())
  dp = [[0,0,0] for i in range(M+1)]
  dp[0][0] = 1
  a = N*(N-1)//2 - N
  a %= mod
  b = a - N + 3
  b %= mod
  c = a - 2*N + 7
  c %= mod
  for i in range(M):
    dp[i+1][0] = sum(dp[i])
    dp[i+1][0] %= mod
    dp[i+1][1] = dp[i][0]*N + dp[i][1]*(N-1) + dp[i][2]*(N-2)
    dp[i+1][1] %= mod
    dp[i+1][2] = dp[i][0]*a + dp[i][1]*b + dp[i][2]*c
    dp[i+1][2] %= mod
  ans = sum(dp[M])
  ans %= mod
  print(ans)

t = int(input())
for _ in range(t):
  solve()