title: Dragging cells with formulas keeping same sequence logic
body: <p>I have some value in cell a1 and these formulas in other cells:</p>
  
  <p>in cell a2: <code>=$a$1+1</code></p>
  
  <p>in cell a3: <code>=$a$1+2</code></p>
  
  <p>in cell a4: <code>=$a$1+3</code></p>
  
  <p>when I select cells a2:a4 and drag down until cell a7 in order to fill the formulas with continuation of the same logic, I get same formulas:</p>
  
  <p>in cell a5: <code>=$a$1+1</code></p>
  
  <p>in cell a6: <code>=$a$1+2</code></p>
  
  <p>in cell a7: <code>=$a$1+3</code></p>
  
  <p>Instead of:</p>
  
  <p>in cell a5: <code>=$a$1+4</code></p>
  
  <p>in cell a6: <code>=$a$1+5</code></p>
  
  <p>in cell a7: <code>=$a$1+6</code></p>
  
  <p>Is there a way to achieve this result by dragging?</p>