Chapter 6: Starting from Randomness

Section 4: Systems of Limited Size and Class 2 Behavior

[Periods in] rules 30 and 45

Maximum periods are often achieved with initial conditions consisting of a single black cell. Particularly for rule 30, however, there are quite a few exceptions. For n = 13, for example, the maximum period is 832 but the period with a single black cell is 260. For rule 45, the maximum possible period discussed above is achieved for n = 9, but does not appear to be achieved for any larger n. (See page 962.)

From Stephen Wolfram: A New Kind of Science [citation]