mod = 998244353

t = int(input())
for _ in range(t):
	n, m = [int(x) for x in input().split()]
	can_place_0 = 1
	can_place_1 = n
	can_place_2 = max(n * (n - 1) // 2 - n, 0)
	can_place_2 %= mod
	
	for _ in range(m - 1):
		next_cp0 = can_place_0 + can_place_1 + can_place_2
		next_cp1 = n * can_place_0
		next_cp1 += (n - 1) * can_place_1 
		next_cp1 += (n - 2) * can_place_2
		next_cp2 = max(n * (n - 1) // 2 - n, 0) * can_place_0
		next_cp2 += ((n - 1) * (n - 2) // 2 - (n - 2)) * can_place_1
		if n >= 4:
			next_cp2 += ((n - 2) * (n - 3) // 2 - (n - 4)) * can_place_2
		
		can_place_0 = next_cp0 % mod
		can_place_1 = next_cp1 % mod
		can_place_2 = next_cp2 % mod
		
	print((can_place_0 + can_place_1 + can_place_2) % mod)