A246308 Number of ON cells at generation n of 2-D cellular automaton in which a cell is ON iff either 1, 2 or 3 of its eight neighbors were ON at previous generation, starting with a single ON cell.

1, 8, 20, 28, 56, 52, 124, 64, 184, 128, 304, 136, 312, 276, 544, 260, 472, 496, 796, 404, 720, 720, 1220, 540, 972, 840, 1724, 808, 1356, 1268, 2056, 1264, 1740, 1772, 2608, 1392, 2308, 1980, 3148, 2108, 2728, 2724, 3776, 2408, 3276, 3200, 4196, 3128, 3872, 3768, 5360, 3408, 4472, 4720, 5720, 4344, 5380, 5144, 6788, 5004, 5836, 6168, 7508, 5704, 7104, 6620, 8916

Offset

0,2

Comments

This is the Rule 252 outer totalistic 8-neighbor 2-D CA.

The first few generations are easy to understand, but then there are complications (hence the keyword "look", which refers to the illustrations).

Links

Table of n, a(n) for n=0..66.

N. J. A. Sloane, Illustration of first 28 generations.

Mathematica

Total@*Total /@ CellularAutomaton[{252, {2, {{2, 2, 2}, {2, 1, 2}, {2, 2, 2}}}, {1, 1}}, {{{1}}, 0}, 66]
ArrayPlot /@ CellularAutomaton[{252, {2, {{2, 2, 2}, {2, 1, 2}, {2, 2, 2}}}, {1, 1}}, {{{1}}, 0}, 28]

Crossrefs

Sequence in context: A295971 A317760 A022757 * A365145 A194218 A339273

Adjacent sequences: A246305 A246306 A246307 * A246309 A246310 A246311

Keyword

nonn,look

Author

N. J. A. Sloane, Aug 23 2014

Status

approved