The key to having things named after you is to give them generic names. Name your thing "array", literally, everywhere in the readme and the code. Then people using it won't have any choice but to say "igushev's array" and that'll stick in the long run.

In competitive programming circles I've heard the basic idea called root or sqrt decomposition.

2-tiered vector.

This is fun, let's have a naming party!

Here's my nomination:

Loop List

This seems like the winner. Although I would tweak it to looped list

That just sounds like a circular linked list. They were probably going for "list of loops", so I think the ambiguity here makes it a bad choice.

tiered_array