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A160721 First differences of A160720. 7
1, 4, 4, 12, 4, 12, 12, 28, 4, 12, 12, 28, 12, 28, 28, 60, 4, 12, 12, 28, 12, 28, 28, 60, 12, 28, 28, 60, 28, 60, 60, 124, 4, 12, 12, 28, 12, 28, 28, 60, 12, 28, 28, 60, 28, 60, 60, 124, 12, 28, 28, 60, 28, 60, 60, 124, 28, 60, 60, 124, 60, 124, 124, 252, 4, 12, 12, 28, 12, 28, 28 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This sequence is related to the Sierpinski triangle and to Gould's sequence A001316. - Omar E. Pol, Jul 23 2009

When written as a irregular triangle in which row lengths are A011782 it appears that right border gives A173033. - Omar E. Pol, Mar 20 2013

LINKS

Table of n, a(n) for n=1..71.

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.]

David Applegate, The movie version

N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS

Index entries for sequences related to toothpick sequences

FORMULA

a(1)=1. Observation: It appears that a(n) = 4*A038573(n-1), n>1. [From Omar E. Pol, Jul 23 2009]. This formula is correct! - N. J. A. Sloane, Jan 23 2016

EXAMPLE

From Omar E. Pol, Mar 20 2013 (Start):

Triangle begins:

1;

4;

4,12;

4,12,12,28;

4,12,12,28,12,28,28,60;

4,12,12,28,12,28,28,60,12,28,28,60,28,60,60,124;

4,12,12,28,12,28,28,60,12,28,28,60,28,60,60,124,12,28,28,60,28,60,60,124,28,60,60,124,60,124,124,252;

(End)

CROSSREFS

Cf. A000120, A001316, A038573, A139250, A139251, A160720, A160722, A160723.

Sequence in context: A273391 A273452 A178182 * A151836 A147582 A162793

Adjacent sequences:  A160718 A160719 A160720 * A160722 A160723 A160724

KEYWORD

nonn,tabf

AUTHOR

Omar E. Pol, May 25 2009, May 29 2009

EXTENSIONS

More terms from R. J. Mathar, Jul 14 2009

STATUS

approved

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Last modified October 15 00:04 EDT 2019. Contains 328025 sequences. (Running on oeis4.)