User blog comment:Primussupremus/more depth in the expansions and theory of my array notation part 2./@comment-30754445-20170518192340/@comment-30754445-20170521174559

If that where so, then we would have:

{3,4,3 |1} = 3 [3^27 arrows] 3

Which can't be right, because we already know that:

{3,4,3 | 1} = {3,4,3} = 3^^3 = 3^27

Let us take it one step at a time:

What would {3,4,3 | 2} be equal to? How many arrows will there be in the final number?

Don't give the first answer which pops into your mind. Proceed carefully by following the actual rules that you've given in your post and using your notation:

If you want a hint:

{3,4,3 | 2} = {3, ____, 3} = 3 [ ___ arrows ] 3