Other examples [of cellular automaton computation]
Rule 152 and rule 144, which effectively compute Ceiling[n/2]
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Ceiling[n/2] and Ceiling[n/4]
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Ceiling[n/4], respectively, are shown below with n = 18
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n = 18 initial black cells.
As discussed on page 989 rule 184 effectively determines whether its initial conditions correspond to a balanced sequence of open and close parentheses. (Rule 132 can be viewed as being like a syntax checker for a regular language; rule 184 for a context-free language.)