I need to determine where the 1's are in a column of data and then identify or concatenate their rows in a cell.

For instance column A looks like the following:

Col A
0
1
0
0
0
1
0

In cell B1 I need to know in string format that the 1's are in rows "2 and 7". This will be part of an error message to alert the user that these rows need fixing.

Thanks for your help.