in google sheets how can I create a string that would give me values of the different cells formatted like: A6:B6, A7:B7, A8:B8 for 7 of them using some sort of loop
You can use a combination of the CONCATENATE, ADDRESS, and ROW functions to achieve this. Here is an example formula that you can use:

=CONCATENATE(ADDRESS(6,1),:,ADDRESS(6,2))

This formula will return the string A6:B6 by using the ADDRESS function to reference cells A6 and B6.

To create the string for multiple rows, you can use a combination of the ROW and CONCATENATE functions along with the above formula. Here is an example formula that you can use:

=CONCATENATE(ADDRESS(ROW(A6),1),:,ADDRESS(ROW(A6),2),, ,ADDRESS(ROW(A7),1),:,ADDRESS(ROW(A7),2),, ,ADDRESS(ROW(A8),1),:,ADDRESS(ROW(A8),2))

This formula will return the string A6:B6, A7:B7, A8:B8 by using the ADDRESS function to reference the cells A6:B6, A7:B7, and A8:B8, and using the CONCATENATE function to combine the strings with commas and spaces in between.

To create the string for a larger number of rows, you can use a loop in Google Apps Script. Here is an example code snippet that you can use:

```
function createString() {
  var numRows = 7;
  var str = ;
  for (var i = 6; i < numRows + 6; i++) {
    str += ADDRESS(i, 1) + : + ADDRESS(i, 2);
    if (i < numRows + 5) {
      str += , ;
    }
  }
  return str;
}
```

This code will create a function called createString that uses a loop to concatenate the strings for each row and adds commas and spaces in between. You can call this function in your Google Sheet to generate the desired string.