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A161910 Y-toothpick 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

The sequence gives the number of Y-toothpicks in the structure after n rounds. A160123 (the first differences) gives the number added at the n-th round.

See the entries A160120, A161830 and A161426 for more information about Y-toothpick 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

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

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Last modified October 16 00:50 EDT 2018. Contains 316252 sequences. (Running on oeis4.)