**Intro: I wanted to add an index to a pivot table**

I wanted to add an index number (1, 2, 3, ...) to the rows of my pivot table. After some experimenting, I ended up adding a column to my source table (`Day Count`

in my example) that counts the unique values of `Day`

. I calculated it with the following array formula in A2: `=SUM(1/COUNTIF($A$2:A2;$A$2:A2))`

(`Ctrl`+`Shift`+`Enter` for the array formula) and pasted it down the table. I added the index (not shown in the picture, but I took the Maximum value of `Day Count`

, which resulted in and index).

Great! Everything merry so far.

**Calculated field strangeness**

I wanted to use the `Day Count`

in a calculated field, but that gave some strange results. I calculated `=MAX('Day Count')`

as calculated field (see screenshot), but instead of 1 (for day A) and 2 (for day B) I got 4 and 6.

I see that 4 is the sum of all day count's for day A and 6 is the sum of all day count's for day B. So I added another test: I created a calculated field that returns 1 (`=1`

). Now I would expect that this would then return 4 and 3, but it returns 1 and 1. Now that seems inconsistent to me.

**My guess as to what's going on**

I think somehow the array formula is expanded during the calculation of the Pivot table. But that's unexpected and possibly an bug in Excel, right?

**Dude! what's your question?**

My question is how to explain the observed behavior. Am I misinterpreting the results or is this a possible bug in Excel?