*3 makes
651.
651 = <<>> <<><>> <<<<>>>>
= b(aa)d
The quoted post used an old notation. In that notation (vertical lineospacial?), 651 is represented by
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. In the depth notation (which came about later) we have
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* *** *
* * * *
*
*
As can be clearly seen from the depth notation, the max depth is four, it has three prime factors, and the representation can neither be symmetric nor alphabetic.
Only one pair of brackets is needed; this can also be seen from the depth notation.