Rule 126 is one of the elementary cellular automaton rules introduced by Stephen Wolfram in 1983 (Wolfram 1983, 2002). It
specifies the next color in a cell, depending on its color and its immediate neighbors.
Its rule outcomes are encoded in the binary representation
. This rule is illustrated
above together with the evolution of a single black cell it produces after 15 steps
(Wolfram 2002, p. 55).

Rule 126 is amphichiral, and its complement is rule
129.

Starting with a single black cell, successive generations , 1, ... are given by interpreting the numbers 1, 7, 27,
127, 387, 1935, 6579, 32767, ... in binary, namely 1, 111, 11011, 1111111, 110000011,
....

Wolfram, S. "Statistical Mechanics of Cellular Automata." Rev. Mod. Phys.55, 601-644, 1983.Wolfram, S. A
New Kind of Science. Champaign, IL: Wolfram Media, pp. 55,
90, and 952,
2002.