Stuck with using lists to solve task

[Larz60+]

this is much easier if you define a function:
example:

# zero = open, 1 = close
doors = [1] * 100        # assumption all doors closed at start ... change to 0 if all open

def change_door(door_list, action_every=1, open_close='open'):
    doornum = action_every - 1

    while doornum < len(doors):
        if open_close == 'open':
            doors[doornum] = 0
        else:
            doors[doornum] = 1
        doornum += action_every

# example open every third door:
change_door(doors, action_every=3, open_close='open')
print(doors)

After running example doors:

Output:
[1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1]