[crazydoggers]

There’s no upper limit, so there’d have to be some set of rules like no sleep(n).

Also given the halting problem, you could write an algorithm that would be impossible to determine if it loops forever.

[plagiarist]

If the results of TREE(n) had specific properties for even n, you could easily check by first calculating TREE(n) and then looking for those properties in the results. Might need a bignum library.