

A161910


Ytoothpick sequence starting at the corner of an infinite hexagon from which protudes a half toothpick with an angle = Pi/6.


1



0, 1, 2, 5, 6, 9, 12, 19, 22, 25, 28, 35, 40, 47, 56, 73
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OFFSET

0,3


COMMENTS

The sequence gives the number of Ytoothpicks in the structure after n rounds. A160123 (the first differences) gives the number added at the nth round.
See the entries A160120, A161830 and A161426 for more information about Ytoothpick sequences.


LINKS

Table of n, a(n) for n=0..15.
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


FORMULA

a(n) = (A160120(n+1)1)/3.


CROSSREFS

Cf. A160120, A160121, A160123, A160406, A161830, A161831.
Sequence in context: A046962 A022486 A267700 * A151920 A160714 A256644
Adjacent sequences: A161907 A161908 A161909 * A161911 A161912 A161913


KEYWORD

more,nonn


AUTHOR

Omar E. Pol, Jun 21 2009


STATUS

approved



