%I
%S 0,1,3,5,7,11,19,25,31,39,51,59,69,79,99,117,127,143,163,171
%N Vtoothpick sequence starting from a Vtoothpick whose central point touch a straight line, as a V.
%C The sequence gives the number of Vtoothpicks after nth stages on hexagonal net. A161421 (the first differences) gives the number added at the nth stage. See A161206 for more information.
%C Also, it appears this is a Htoothpick sequence in the first quadrant on the square grid, starting with a Dtoothpick from the point (0,0). The sequence gives the number of toothpicks and Dtoothpicks after nth stage. A161421 (the first differences) gives the number added at the nth 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), 157191. [There is a typo in Theorem 6: (13) should read u(n) = 4.3^(wt(n1)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
