versioning difference 42.x vs 13.x

Hi every body,
What’s the difference between 13.x versioning vs 42.x?
Is that next later releases continue from 42 or from 13?
Thanks in advance.

The steps are: …, 13.1, 13.2, Leap 42.1, Leap 42.2, the future.
No comment on the logic behind this, these are the facts.

The 42 versioning is just fun. It was taken from the Hitchhiker’s Guide to the Galaxy. One of the first Suse versions was a 4.2.