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A161420 V-toothpick sequence starting from a V-toothpick 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 (list; graph; refs; listen; history; text; internal format)



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.

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.


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

N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS


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




Omar E. Pol, Jun 10 2009



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Last modified August 19 23:35 EDT 2017. Contains 290821 sequences.