I'm trying to create an ARRAYFORMULA for a column that will display text if the value in Column A is unique, and if it is a duplicate display text indicating if the value is the first occurrence of a duplicate or a subsequent occurrence of it.

I've been able to do this with a (probably overly complicated) formula that works as a fill, but because it uses INDIRECT, it can't be iterated over using ARRAYFORMULA.

I came across the following conditional formatting formula on