That would depend on the construction of course. Everything can be broken down, the question is what you get of it.
The Fibonacci sequence is simple enough to make people guessing, and rises fairly swiftly, so anything beyond ten becomes too impractical for use. You could encode something like an elevator with this, the destruction of the mechanism could destroy the whole cabin and drop the passengers down a _very_ deep hole.
the door is simply that, a door, litterly propped up against the wall if you break the door then you cant go anywhere.you can move the door. you can do whatever but if you break it then you go nowhere...
Manfred, your idea of an elevator intrigues me. if continuing along this line of thinking you could really have something simmilar to the glass elevator of willy wonka (sorry about bring him in here, but it works) where the numbers are listed as buttons but not in order of the sequence thus figuring out the sequence is impractical yet time consuming.
you could litterly hit a button in the correct sequence such as with the library on the 4th "door" such as hitting the buttons 1,1,2,3 thus entering the library. thus making higher numbers and combinations possible... Go to Comment
The PCs traveling along the road/path/trail begin to hear a low droning sound. As they approach they find their path obstructed by hundred of thousands of droning insects. Locusts swarm though the air, feasting on the grass and plants. Passage will be slowed, but the insects pose no threat to the party, aside from being crunchy and disgusting underfoot, climbing into pouches and eating exposed food goods.