The non-trivial method uses a pattern you might not have seen yet but has been discussed.
You know how to look up a number c from column 0 or 1. One way is to take a[t] from c in [0,1] or [1,1], divide the remainder by two and add that to the column to get c in another column.
The value c can be looked up in many columns this way.
This gives enough information to find a, x and n.