title: Google spreadsheet formula refer to cell with address to another cell
body: <p>Good day! Could you please help me with the following formula. I'm trying to calculate a number of non-empty cells after specific words. 
  With a formula, I defined the address of the last cells after which I need to start count. In my case, In Cell <b>O1</b> I defined the start position, for example, <b>A15</b>, the end position is always <b>A</b>. So the formula will be 
  <b> =COUNTA(A15:A) </b>
  But in my case, it could be a different start position. So, I'm trying to use formula 
  <b>=COUNTA(CONCAT(INDIRECT(O1),":A") </b>
  but it does not work. Please help :)
  Thanks in advance!</p>