A161832 a(n) = (A161830(n+1)-1)/2.

0, 1, 2, 4, 5, 7, 9, 13, 15, 17, 19, 23, 26, 30, 35, 44, 49, 51

Offset: 0

Author

Omar E. Pol, Jun 20 2009

Keywords

• more
• nonn

Comments

The sequence gives the number of Y-toothpicks in the structure after n rounds. A161833 (the first differences) gives the number added at the n-th round.

See the Y-toothpick sequence A160120 and A161830 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

Crossrefs

Cf. A139250, A160120, A160406, A161830, A161831, A161833.