User blog comment:QuasarBooster/Duplicative Array Notiation/@comment-25337554-20160322100102/@comment-24923514-20160328001631

(Sorry for the delay) Think about the pre-problem with the ones. If I was to mark the 3, 2, and 1 with something like an asterisk then we'd have:

<2>[3*,2*,1*]

Now for each of the marked items, from left to right, we replace with the current expression without any asterisks. So going step-by-step:

<2>[3*,2*,1*] = <2>[<2>[3,2,1],2*,1*], <2>[<2>[3,2,1],2*,1*] = <2>[<2>[3,2,1],<2>[<2>[3,2,1],2,1],1*], <2>[<2>[3,2,1],<2>[<2>[3,2,1],2,1],1*] = <2>[<2>[3,2,1],<2>[<2>[3,2,1],2,1],<2>[<2>[3,2,1],<2>[<2>[3,2,1],2,1],1]]

As each marked element is getting replaced, the total expression itself is changing, creating a fractalic pattern as we go on. I hope I helped at least somewhat!