A188343 Number of "ON" cells at n-th stage in simple 2-dimensional cellular automaton (see Comments for precise definition).

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

Offset: 0

Author

Nathaniel Johnston, Mar 28 2011

Keywords

• nonn

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 n-1.

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 n-1.

First differs from A160118 at a(13).

Links

• 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

Crossrefs

Cf. A160118.

Formula

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