The pilot light.. If you cant see it you should be able to feel it. The stove top should be a little warmer than, say the dishwasher. If none of your burners are coming on I would suspect that its not lit.
The Collatz problem, or Collatz conjecture (aka the 3n+1) is a crazy piece of math that is, at current, unsolvable. All I know about it is that it asks if a specific kind of number sequence will always end the same way regardless of which number you start with. I think this is a correct example:
7, 22, 11, 34, 17, 52, 26, 13, 40, 20, 10, 5, 16, 8, 4, 2, 1
Thats ALL I know about this. Please dont ask me about fibonacci.