A246310 Number of ON cells at generation n of 2-D cellular automaton in which a cell is ON iff either 1 or 4 of its eight neighbors were ON at previous generation, starting with a single ON cell.

1, 8, 8, 25, 4, 32, 32, 100, 25, 61, 88, 208, 112, 164, 232, 380, 188, 304, 341, 596, 437, 576, 528, 696, 553, 749, 736, 924, 1016, 1060, 1161, 1372, 1200, 1388, 1456, 1720, 1493, 1761, 1660, 2072, 1781, 2084, 1973, 2732, 2252, 2596, 2552, 3121, 2684, 3145, 2972, 3828, 3132, 3588, 3480, 4061, 3772, 4073, 4009, 4929, 4264, 4996, 4845, 5493, 5160, 5804, 5156

Offset

0,2

Comments

This is the Rule 780 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.

N. J. A. Sloane, On the Number of ON Cells in Cellular Automata, arXiv:1503.01168, 2015

Mathematica

Total@*Total /@ CellularAutomaton[{780, {2, {{2, 2, 2}, {2, 1, 2}, {2, 2, 2}}}, {1, 1}}, {{{1}}, 0}, 66]
ArrayPlot /@ CellularAutomaton[{780, {2, {{2, 2, 2}, {2, 1, 2}, {2, 2, 2}}}, {1, 1}}, {{{1}}, 0}, 28]

Crossrefs

Cf. A253086 (5-celled analog).

Sequence in context: A160239 A211017 A037018 * A318542 A319089 A003873

Adjacent sequences: A246307 A246308 A246309 * A246311 A246312 A246313

Keyword

nonn,look

Author

N. J. A. Sloane, Aug 23 2014

Status

approved