David Applegate, Omar E. Pol and N. J. A. Sloane, <a href="http://neilsloane.com/docA000695/tootha000695_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.]

David Applegate, Omar E. Pol and N. J. A. Sloane, <a href="http://neilsloane.com/doc/tooth.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.]

N. J. A. Sloane, <a href="http://neilsloane.com/docwiki/toothlist.htmlCatalog_of_Toothpick_and_CA_Sequences_in_OEIS">Catalog of Toothpick and Cellular Automata Sequences in the OEIS</a>

David Applegate, Omar E. Pol and N. J. A. Sloane, <a href="http://www.research.attneilsloane.com/~njas/doc/tooth.pdf">The Toothpick Sequence and Other Sequences from Cellular Automata</a>

N. J. A. Sloane, <a href="http://www.research.attneilsloane.com/~njas/doc/toothlist.html">Catalog of Toothpick and Cellular Automata Sequences in the OEIS</a>

_Omar E. Pol (info(AT)polprimos.com), _, Jun 21 2009

Number of rhombuses in the Y-toothpick structure of A160120 after n rounds.

0, 0, 3, 3, 9, 9, 15, 21, 33, 39

0,3

David Applegate, Omar E. Pol and N. J. A. Sloane, <a href="http://www.research.att.com/~njas/doc/tooth.pdf">The Toothpick Sequence and Other Sequences from Cellular Automata</a>

N. J. A. Sloane, <a href="http://www.research.att.com/~njas/doc/toothlist.html">Catalog of Toothpick and Cellular Automata Sequences in the OEIS</a>

Cf. A139250, A160120, A160124, A161419, A161418, A161836.

more,nonn

Omar E. Pol (info(AT)polprimos.com), Jun 21 2009

approved