title: using counta in offset and dealing with cells with no value
body: <p>I am using offset to get a range of the last 7 entries in a column which updates automatically when I add data to it.  However, to be able to automate this as much as possible I have to use a formula to determine if there is a value to display in that cell. This causes the cell to be not-empty and thus the offset isn't working. Any workaround for this?</p>
  
  <p>I copy the data from Sheet1 into another sheet because I need to hide the columns in Sheet1, and therefor can't create a sparkline for those values anymore.  Copying the data into column B on Sheet 2:  </p>
  
  <pre><code>=IF(Sheet1!O18&lt;&gt;"";Sheet1!O18;"")
  </code></pre>
  
  <p>Using the offset:</p>
  
  <pre><code>=OFFSET(Sheet2!$B$3;COUNTA(Sheet2!$B:$B)-7;0;7)
  </code></pre>