A161426 Y-toothpick sequence starting at the outside corner of an infinite triangle-shaped polygon as the sieve of A160120 after 2^k rounds.

0, 1, 4, 7, 14, 19, 26, 35, 52, 63, 70

Offset: 0

Author

Omar E. Pol and David Applegate, Jun 20 2009

Keywords

• more
• nonn

Comments

The sequence gives the number of Y-toothpicks after n rounds. A161427 (the first differences) gives the number added at the n-th round.

See the entries A160120, A139250 and A153006 for more information.

Links

• David Applegate, Omar E. Pol and N. J. A. Sloane, The Toothpick Sequence and Other Sequences from Cellular Automata, 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, Catalog of Toothpick and Cellular Automata Sequences in the OEIS
• David Applegate, The movie version

Crossrefs

Cf. A000079, A139250, A153006, A160120, A161427, A161830.