A246309 Number of ON cells at generation n of 2-D cellular automaton in which a cell is ON iff either 1, 2 or 4 of its eight neighbors were ON at previous generation, starting with a single ON cell.

1, 8, 20, 32, 44, 64, 65, 149, 96, 184, 161, 312, 236, 356, 312, 545, 397, 552, 524, 821, 565, 872, 688, 1129, 929, 1152, 1245, 1440, 1460, 1485, 1737, 1904, 1592, 2240, 1757, 2433, 2080, 2520, 2404, 2956, 2620, 3200, 3041, 3629, 3133, 3928, 3513, 4385, 3668, 4469, 4300, 4748, 4309, 5420, 4917, 5841, 5232, 6161, 5521, 6853, 5701, 7448, 6088, 8241, 6165, 7964, 6945

Offset

0,2

Comments

This is the Rule 828 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[{828, {2, {{2, 2, 2}, {2, 1, 2}, {2, 2, 2}}}, {1, 1}}, {{{1}}, 0}, 66]
ArrayPlot /@ CellularAutomaton[{828, {2, {{2, 2, 2}, {2, 1, 2}, {2, 2, 2}}}, {1, 1}}, {{{1}}, 0}, 28]

Crossrefs

Sequence in context: A194218 A339273 A017617 * A363518 A038522 A267435

Adjacent sequences: A246306 A246307 A246308 * A246310 A246311 A246312

Keyword

nonn,look

Author

N. J. A. Sloane, Aug 23 2014

Status

approved