Registered: Oct 2003
Posts: 103

Occasionally someone asks about the caption on p.178

"...now [it] takes the center cell to become black only if it has exactly three neighbors. If it has 1,2 or 4 neighbors it stays the same color it was before, and if it has 5 or more black neighbors then it becomes white on the next step."

Another way to say this is that it is an outer totalistic rule. When the center cell is white, it takes three black neighbors for the center cell to turn black and otherwise stays white. When the center cell is black, it takes 5 or more black neighbors for the center cell to turn white, otherwise it stays black.

This is code 746, and in modern Mathematica it is
ArrayPlot[CellularAutomaton[{746, {2, {{2, 2, 2}, {2, 1, 2}, {2, 2, 2}}}, {1, 1}}, {Table[1, {1}, {7}], 0}, {{{400}}}]] 

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