four_four.py

num_list = [2, 4, 1, 6, 40, 2, 24, 3, 1, 5, 6, 8, 12, 9, 31, 45, 7, 14, 19, 20] 
count = 5 
paritioned_list = [] 
for i in range(count-1): 
    paritioned_list.append(num_list[i*count:(i+1)*count]) 

two_d_4x4 = [
    list(set(first_list).intersection(second_list))
    for first_list in paritioned_list
    for second_list in paritioned_list
]