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A187221 First differences of A187220. 5
0, 1, 2, 4, 8, 8, 8, 16, 24, 16, 8, 16, 24, 24, 32, 56, 64, 32, 8, 16, 24, 24, 32, 56, 64, 40, 32, 56, 72, 80, 120, 176, 160, 64, 8, 16, 24, 24, 32, 56, 64, 40, 32, 56, 72, 80, 120, 176, 160, 72, 32, 56, 72, 80, 120, 176, 168, 112, 120, 184, 224, 280, 416, 512, 384, 128, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Number of gulls (or G-toothpicks) added at n-th stage to the gullwing structure of A187220.

Apparently this is the connection between A147582 and A139251. - Omar E. Pol, Mar 11 2011

LINKS

Table of n, a(n) for n=0..66.

David Applegate, The movie version

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(0)=0. a(1)=1. It appears that a(n) = 2*A139251(n-1), for n >= 2.

EXAMPLE

If written as an irregular triangle begins:

0,

1,

2,

4,

8,8,

8,16,24,16,

8,16,24,24,32,56,64,32,

8,16,24,24,32,56,64,40,32,56,72,80,120,176,160,64,

...

Also there is another version in which the layout of the irregular triangle was adjusted to reveal that the columns become constant:

.0,

.1,

.2,

.4,8,

.8,8,16,24,

16,8,16,24,24,32,56,64,

32,8,16,24,24,32,56,64,40,32,56,72,80,120,176,160,

64,8,16,24,24,32,56,64,40,32,56,72,80,120,176,160,72,32,56,72,80...

CROSSREFS

Cf. A139250, A139251, A147582, A187211, A187220.

Sequence in context: A178573 A162794 A172305 * A129280 A103224 A198346

Adjacent sequences:  A187218 A187219 A187220 * A187222 A187223 A187224

KEYWORD

nonn

AUTHOR

Omar E. Pol, Mar 07 2011, Mar 09 2011

STATUS

approved

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Last modified November 18 10:08 EST 2019. Contains 329261 sequences. (Running on oeis4.)