

A151921


Net gain in number of ON cells at stage n of the cellular automaton described in A079317.


2



0, 1, 4, 0, 12, 8, 20, 8, 44, 40, 52, 40, 76, 64, 100, 64, 172, 168, 180, 168, 204, 192, 228, 192, 300, 288, 324, 288, 396, 360, 468, 360, 684, 680, 692, 680, 716, 704, 740, 704, 812, 800, 836, 800, 908, 872, 980, 872, 1196
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OFFSET

0,3


COMMENTS

Start with cell (0,0) ON; at each succeeding stage the cells that share exactly one edge with an active cell change their state.


LINKS

Table of n, a(n) for n=0..48.
David Applegate, Omar E. Pol and N. J. A. Sloane, The Toothpick Sequence and Other Sequences from Cellular Automata, Congressus Numerantium, Vol. 206 (2010), 157191. [There is a typo in Theorem 6: (13) should read u(n) = 4.3^(wt(n1)1) for n >= 2.]
N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS


FORMULA

If n is even, a(n) = A079315(n) = A151914(n/2); if n is odd, a(n) = A147582((n+1)/2)  A151914((n1)/2).
First differences of A079317.


CROSSREFS

Cf. A079317, A079315, A139250, A151914, A147582.
Sequence in context: A273795 A273858 A273485 * A273838 A273761 A273424
Adjacent sequences: A151918 A151919 A151920 * A151922 A151923 A151924


KEYWORD

sign


AUTHOR

N. J. A. Sloane, Aug 05 2009, Aug 06 2009


STATUS

approved



