A151731 - OEIS

A151731

Number of ON states after n generations of cellular automaton based on square grid with each cell adjacent to its eight neighbors.

0, 2, 6, 14, 20, 32, 40, 54, 70, 94, 108, 128, 152, 172, 188, 224, 256, 300, 344, 380, 416, 464, 504, 552, 598, 658, 728, 772, 816, 880, 940, 1000, 1076, 1148, 1212, 1276, 1360, 1454, 1556, 1624, 1708, 1796, 1912, 2004, 2124, 2250, 2376, 2480

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

COMMENTS

A cell is turned ON if exactly two of its eight neighbors is ON. An ON cell remains ON forever.

We start with two edge-adjacent ON cells.

LINKS

Rémy Sigrist, Table of n, a(n) for n = 0..8192

Rémy Sigrist, PARI program for A151731

Rémy Sigrist, Illustration of the structure at stage 512

PROG

(PARI) See Links section.

CROSSREFS

See A151725, A151726 for the same CA except that exactly one neighbor must be ON for a cell to turn ON.

Cf. A151732, A151733, A151734.

Sequence in context: A130800 A067262 A107369 * A009779 A086666 A032383

Adjacent sequences: A151728 A151729 A151730 * A151732 A151733 A151734

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jun 15 2009

STATUS

approved