@user What about this, then? Try it online!

@Leo Nice!

I think I get the +ḋ3, but I'm still trying to wrap my head around the zM- part

Oh, I see, ttN gave you [3..] to zip with instead of the indices

Exactly

Honestly, I was having trouble wrapping my head around your zom+m-, so I implemented it in a way that made more sense to me ^^"

Yeah, that whole thing was just a misguided attempt at translating literally from Haskell