Let's be sure about what we are looking at in this structure. What appear to be crossed out parentheses are actually single horizontal bond symbols passing through each parenthesis. The grouping symbols are necessary to show that the subscript "n" belongs to the bonded molecules within the parentheses. This type of notation is not illustrated in any of our Code examples. I am away from my source materials at the moment; I will get back to you about proper transcription of this later today.