User blog comment:Boboris02/Quickly-extending linear hydra/@comment-30118230-20161112153037/@comment-25601061-20161113014517

There's an infinite loop.

With the last rule, we solve the hydra, but at each step (excluding if the hydra has only 1 entry remaining or if the hydra has a group of 0's at the start), the last entry is increased by 1 (when the hydra has a group of 0's at the start the last entry is increased by the number of 0's in the group). So after everything but the last entry is solved, the last entry will have increased, and the cycle repeats again, the last entry increasing more and more each time, and the hydra becomes unsolvable.