

A188343


Number of "ON" cells at nth stage in simple 2dimensional cellular automaton (see Comments for precise definition).


2



0, 1, 9, 13, 41, 45, 73, 85, 169, 173, 201, 213, 297, 317, 441, 485, 681, 685, 713, 725, 809, 829, 953, 997, 1193, 1213, 1353, 1397, 1689, 1773, 2201, 2309, 2737, 2765, 2817, 2845, 2953, 2989, 3113
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OFFSET

0,3


COMMENTS

On the infinite square grid, we start at stage 0 with all square cells in the OFF state.
At stage 1 we turn ON a single cell in the central position.
For n>1, if n is even, at stage n we turn ON all the OFF neighboring cells from cells that were turned ON at stage n1.
For n>1, if n is odd, at stage n we turn ON all the OFF cells that have exactly one neighbor that was turned ON at stage n1.
First differs from A160118 at a(13).


LINKS

Table of n, a(n) for n=0..38.
Nathaniel Johnston, 13th generation of this sequence, where it first differs from A160118. Cells in green were newly turned on in generation 13 and are also turned on in generation 13 of A160118. Cells in red are newly turned on but are not turned on in A160118.
Index entries for sequences related to cellular automata


FORMULA

For n even, use Generations rule "/12345678/250". For n odd, use Generations rule "/1/250".


CROSSREFS

Cf. A160118.
Sequence in context: A219257 A200537 A160118 * A160117 A068984 A146016
Adjacent sequences: A188340 A188341 A188342 * A188344 A188345 A188346


KEYWORD

nonn


AUTHOR

Nathaniel Johnston, Mar 28 2011


STATUS

approved



