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A160802 Toothpick sequence in Fibonacci spiral (see Comments lines for definition). 5
0, 1, 3, 7, 11, 15, 21, 25, 28, 30, 33, 37, 38, 40, 43, 45, 47, 51, 57, 62, 65, 70, 75, 77, 79, 81, 83, 86, 90, 93, 95, 98, 102, 106, 111, 119, 127, 131, 132, 134, 137, 140, 144, 151, 159, 164, 168, 175, 184, 194, 209, 231, 243, 250 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

On the infinite square grid we draw a Fibonacci spiral starting with 3,3,6,9,15,24,... (Note that each edge has length = A000045(k)*3, for k>0). We start at stage 0 with no toothpicks. At stage 1 we place a toothpick of length 2 in a orthogonal direction, in the center of the Fibonacci spiral. At stage 2 we place 2 toothpicks. And so on...

The sequence gives the number of toothpicks in the Fibonacci spiral after n stages. A160803 (the first differences) gives the number added at the n-th stage. See A160800 and A139250 for more information about toothpick sequences.

LINKS

Nathaniel Johnston, Table of n, a(n) for n = 0..256

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

Nathaniel Johnston, C script for computing terms

CROSSREFS

Cf. A000045, A139250, A139251, A160426, A160427, A160800, A160801, A160803.

Sequence in context: A022797 A190884 A109507 * A170888 A182838 A163094

Adjacent sequences:  A160799 A160800 A160801 * A160803 A160804 A160805

KEYWORD

nonn

AUTHOR

Omar E. Pol, May 26 2009

EXTENSIONS

Terms after a(12) from Nathaniel Johnston, Mar 30 2011

STATUS

approved

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Last modified February 25 04:05 EST 2018. Contains 299630 sequences. (Running on oeis4.)