I have a few hundred rows with only values in column A.
I want to get groups of 10 values from column A and make this a comma separated string on every multiple of 10 row in column B (row 1,10,21 etc).
I simply want to drag and copy the same formula in each cell of column B and not have to manually insert a formula on every multiple of 10.

I DON'T want to use a Macro, just a worksheet function.
So the end result of calculated column B values should be:

A B
3 3,3,1,4,5,6,6,7,2,2
3
1
4
5
6
6
7
2
2
5 5,7,8,9,4,5,6,7,9,3
7
8
9
4
5
6
7
9
3
4 4,5,6,7,8
5
6
7
8