title: Insert Formula in blank cells of specific column
body: <p>I want to insert a formula into any blank cells in column A , the formula is</p>
  
  <pre><code>=vlookup([cell ref],worksheet,A:Z,2,0) 
  </code></pre>
  
  <p>where the cell ref is the adjacent cell in column C. I can't overwrite the entire column as some of the values the formula would return are no longer available. As column C expands each week i can't put a set cell number.</p>