Beaver Math Olympiad
Beaver Mathematical Olympiad (BMO) is an attempt to re-formulate the halting problem for some particular Turing machines as a mathematical problem in a style suitable for a hypothetical math olympiad.
The purpose of the BMO is twofold. First, statements where every non-essential details (e.g. related to tape encoding, number of steps, etc) are discarded are more suitable to be shared with mathematicians who perhaps are able to help. Second, it's a way to jokingly highlight how a hard question could appear deceptively simple.
Currently existing BMO problems represent machines: