

A172308


Ltoothpick sequence in the first quadrant.


6



0, 1, 3, 5, 7, 11, 15, 17, 21, 27, 33, 41, 47, 59, 69, 75, 79
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,3


COMMENTS

The same as A172310 and A172304, but starting from half Ltoothpick in the first quadrant.
Note that if n is odd then we add the small Ltoothpicks to the structure, otherwise we add the large Ltoothpicks to the structure.
We start at stage 0 with half Ltoothpick: A segment from (0,0) to (1,1).
At stage 1 we place a small Ltoothpick at the exposed toothpick end.
At stage 2 we place two large Ltoothpicks.
At stage 3 we place two small Ltoothpicks.
At stage 4 we place two large Ltoothpicks.
And so on...
The sequence gives the number of Ltoothpicks after n stages. A172309 (the first differences) gives the number of Ltoothpicks added at the nth stage.


LINKS

Table of n, a(n) for n=0..16.
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, A153000, A160120, A160170, A160172, A161206, A161328, A172304, A172305, A172306, A172307, A172309, A172310, A172311, A172312, A172313.
Sequence in context: A139252 A076245 A318953 * A190812 A238738 A059748
Adjacent sequences: A172305 A172306 A172307 * A172309 A172310 A172311


KEYWORD

more,nonn


AUTHOR

Omar E. Pol, Feb 06 2010


STATUS

approved



