Ошибка в индексе кортежа

import time, random
n = 7
m = 7
surv_rule = [2, 3]
birth_rule = [3]
start_pos = None
fps = 1
bg_shade = 1
fg_shade = 3
lag_txt = '''Too big delay, choose a lower fps or
field size next time to get stable fps.'''
shades = ('  ', '░░', '▒▒', '▓▓', '██')
entry = [[random.randint(0, 1) * (0 < i < n - 1 and 0 < j < m - 1) 
          for j in range(m)]
         for i in range(n)] if start_pos == None else start_pos, 
memory = [[0 for j in range(m)] for i in range(n)]
while True:
    start = time.time()
    [print(''.join(map(str,entry[i][1:-1])).replace(
        '0',shades[bg_shade]).replace(
            '1',shades[fg_shade])) for i in range(1, n-1)]
    print('\n'*3)
    for x in range(1, n-1):
        for y in range(1, m-1):
            memory[x][y] = sum([sum([entry[x + i][y + j]
                                     for j in range(-1, 2)])
                                for i in range(-1, 2)]) - entry[x][y]
    for i in range(n):
        for j in range(m):
            entry[i][j] = int(entry[i][j] == 1 and memory[i][j] in surv_rule or
                              entry[i][j] == 0 and memory[i][j] in birth_rule)
    time.sleep(1/fps)
    end = time.time()
    if 1/fps/(end-start) < 0.75:
        print(lag_txt,end-start)