This doesn't seem to be specificed in the docs and the FAQ.

I see this suggested in Let's Plan the Second Iteration of the Stack Exchange Quality Project! (10.2016) and mentioned as an existing feature (!) in Un-delete count off (10.2010).

The corresponding FAQ How does deleting work? What can cause a post to be deleted, and what does that actually mean? What are the criteria for deletion? suggested as a duplicate doesn't answer this question -- it only says that N votes are needed, nothing about their dynamic.