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A160123 a(n) = A160121(n+1)/3. 6

%I #10 Feb 24 2021 02:48:18

%S 1,1,3,1,3,3,7,3,3,3,7,5,7,9,17,9,3,3,7,5,7,9,17,11,7,9,17,17,19,23,

%T 39,27,7,3,7,5,7,9,17,11,7,9,17,17,19,23,39,29,11,9,17,17,19,25,43,39,

%U 25,23,39,45,47,57,93,77,23,3,7,5,7,9

%N a(n) = A160121(n+1)/3.

%C Also, first differences of A161910. [From _Omar E. Pol_, Jun 21 2009]

%H David Applegate, Omar E. Pol and N. J. A. Sloane, <a href="/A000695/a000695_1.pdf">The Toothpick Sequence and Other Sequences from Cellular Automata</a>, 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.]

%H N. J. A. Sloane, <a href="/wiki/Catalog_of_Toothpick_and_CA_Sequences_in_OEIS">Catalog of Toothpick and Cellular Automata Sequences in the OEIS</a>

%e Note that this can be written as a triangle:

%e 1;

%e 1;

%e 3;

%e 1,3;

%e 3,7,3,3;

%e 3,7,5,7,9,17,9,3;

%e 3,7,5,7,9,17,11,7,9,17,17,19,23,39,27,7;

%e 3,7,5,7,9,17,11,7,9,17,17,19,23,39,29,11,9,17,17,19,25,43,39,25,23,39,45,47,57,93,77,23;

%e 3,7,5,7,9,...

%Y Y-toothpick sequence: A160120. Cf. A160121, A160122.

%Y Cf. A139250, A139251. [From _Omar E. Pol_, Jun 16 2009]

%Y Cf. A161831, A161427, A161910. [From _Omar E. Pol_, Jun 21 2009]

%K nonn

%O 1,3

%A _Omar E. Pol_, May 02 2009, May 21 2010

%E More terms from _Omar E. Pol_, Jun 16 2009

%E Extended by _R. J. Mathar_, Feb 05 2010

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Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)