Count duplicates over a certain time

[Jasel]

I have a table attached to a date dimension where I want to count the number of duplicates of Column1 - figure it to be an integer.

A value in Column1 repeats itself without any kind of patter.  I need to figure out how many times a value repeats itself but only repeats itself after X amount of months.

Example:

555	6/12/2017
556	6/17/2017
555	7/17/2017
556	9/12/2017
555	10/12/2017
555	11/12/2017
555	12/28/2017
555	1/28/2017
556	1/28/2018

So 555 duplicate count would equal 1, and 556 would be 2.

I'd assume there must be some kind of DAX that can be used for this formula however I haven't been able to figure it out exactly.

[v-chuncz-msft]

@Jasel,

You may add a measure as follows.

Measure =
SUMX (
    Table1,
    VAR d = Table1[Date]
    RETURN
        IF (
            COUNTROWS (
                FILTER (
                    Table1,
                    Table1[Date]
                        >= DATE ( YEAR ( d ), MONTH ( d ) - 1, 1 )
                        && Table1[Date] < d
                )
            )
                = 0,
            1
        )
)
    - 1

[Jasel]

I'm trying this now @v-chuncz-msft, but am not seing the measure once I pusblish the tabluar model and refresh Power BI.