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 A161420 V-toothpick sequence starting from a V-toothpick whose central point touch a straight line, as a V. 2

%I

%S 0,1,3,5,7,11,19,25,31,39,51,59,69,79,99,117,127,143,163,171

%N V-toothpick sequence starting from a V-toothpick whose central point touch a straight line, as a V.

%C The sequence gives the number of V-toothpicks after n-th stages on hexagonal net. A161421 (the first differences) gives the number added at the n-th stage. See A161206 for more information.

%C Also, it appears this is a H-toothpick sequence in the first quadrant on the square grid, starting with a D-toothpick from the point (0,0). The sequence gives the number of toothpicks and D-toothpicks after n-th stage. A161421 (the first differences) gives the number added at the n-th stage. For more information see A182838.

%H 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.]

%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>

%Y Cf. A139250, A160120, A160406, A161206, A161328, A161412, A161421, A161422, A161423, A182832, A182838.

%K more,nonn

%O 0,3

%A _Omar E. Pol_, Jun 10 2009

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Last modified August 6 15:50 EDT 2020. Contains 336255 sequences. (Running on oeis4.)