

A161420


Vtoothpick sequence starting from a Vtoothpick whose central point touch a straight line, as a V.


2



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

0,3


COMMENTS

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.
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.


LINKS

Table of n, a(n) for n=0..19.
David Applegate, Omar E. Pol and N. J. A. Sloane, The Toothpick Sequence and Other Sequences from Cellular Automata, 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.]
N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS


CROSSREFS

Cf. A139250, A160120, A160406, A161206, A161328, A161412, A161421, A161422, A161423, A182832, A182838.
Sequence in context: A093929 A144427 A082603 * A071997 A093442 A155008
Adjacent sequences: A161417 A161418 A161419 * A161421 A161422 A161423


KEYWORD

more,nonn,changed


AUTHOR

Omar E. Pol, Jun 10 2009


STATUS

approved



