First, in terms of tetration (formula_16) alone::formula_17where the number of 3s in the expression on the right is:formula_18Now each tetration (formula_19) operation reduces to a "tower" of exponentiations (formula_20) according to the definition:formula_21Thus,:formula_22becomes, solely in terms of repeated "exponentiation towers",:formula_23and where the number of 3s in each tower, starting from the leftmost tower, is specified by the value of the next tower to the right.