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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 (list; graph; refs; listen; history; text; internal format)
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), 157-191. [There is a typo in Theorem 6: (13) should read u(n) = 4.3^(wt(n-1)-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((n-1)/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

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Last modified November 20 14:54 EST 2019. Contains 329337 sequences. (Running on oeis4.)