A162797 a(n) = difference between the number of toothpicks of A139250 that are orthogonal to the initial toothpick and the number of toothpicks that are parallel to the initial toothpick, after n even rounds.

1, 1, 5, 1, 5, 5, 17, 1, 5, 5, 17, 5, 17, 21, 49, 1, 5, 5, 17, 5, 17, 21, 49, 5, 17, 21, 49, 21, 53, 81, 129, 1, 5, 5, 17, 5, 17, 21, 49, 5, 17, 21, 49, 21, 53, 81, 129, 5, 17, 21, 49, 21, 53, 81, 129

Offset

1,3

Comments

It appears that a(2^k) = 1, for k >= 0. [From Omar E. Pol, Feb 22 2010]

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..94

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

Formula

a(n) = A162796(n) - A162795(n).

Example

Contribution from Omar E. Pol, Feb 22 2010: (Start)
If written as a triangle:
1;
1,5;
1,5,5,17;
1,5,5,17,5,17,21,49;
1,5,5,17,5,17,21,49,5,17,21,49,21,53,81,129;
1,5,5,17,5,17,21,49,5,17,21,49,21,53,81,129,5,17,21...
Rows converge to A173464.
(End)
Contribution from Omar E. Pol, Apr 01 2011 (Start):
It appears that the final terms of rows give A000337.
It appears that row sums give A006516.
(End)

Crossrefs

Cf. A139250, A139251, A159791, A159792, A162793, A162794, A162795, A162796.

Cf. A000337, A058922, A173464. [From Omar E. Pol, Feb 22 2010]

Sequence in context: A306577 A143969 A198366 * A087232 A151780 A054244

Adjacent sequences: A162794 A162795 A162796 * A162798 A162799 A162800

Keyword

nonn

Author

Omar E. Pol, Jul 14 2009

Extensions

Edited by Omar E. Pol, Jul 18 2009

More terms from Omar E. Pol, Feb 22 2010

More terms (a(51)-a(55)) from Nathaniel Johnston, Mar 30 2011

Status

approved