title_body: Printing ebook on A4 paper
upvoted_answer: would it not need to be
  32, 1, 2, 31 (assuming flipping on the short edge of the A4) that way 1 and 2 will be on opposite sides of page and so will 31 and 32.
  
  Also something else to think about is odd number of pages in the book or non multiples of 2...
  take 10 pages for example... 
  
  [10, 1, 2, 9] 
  
  [8, 3, 4, 7]
  
  [6,5,?,?]
  
  you would have 2 empty pages in the middle of the book
  so to counter that you'd probably need to take that into account
  
  ALTHOUGH this isn't taking into account that you will cut the pages in the center. That would be binding in the middle
  
  Thinking in terms of binding page by page...
  
  Having 1 and 2 together won't really work seeing as you want them to be back to back
  
  back to 10 example
  
  [4, 1, 2, 3] or could be [3, 1, 2, 4] or [1, 3, 4, 2], etc. But I'd do first one to keep the cut edges at the binding side
  
  [8, 5, 6, 7]
  
  [?, 9, 10, ?] or [?, 10, 9, ?] or [9, ?, ?, 10] or [10, ?, ?, 9] where ? is an empty page.