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A170926 Total number of squares and rectangles at the n-th stage in the corner toothpick structure (see A152890, A153006). 3
0, 0, 1, 3, 4, 5, 10, 17, 20, 21, 25, 30, 33, 40, 58, 77, 84, 85, 89, 94, 97, 104, 121, 138, 145, 151, 164, 177, 190, 222, 278, 325, 340, 341, 345, 350, 353, 360, 377, 394, 401, 407, 420, 433, 446, 478, 533, 578, 593, 599, 612, 625, 638, 669, 720, 761, 781, 806, 845, 884, 942 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..60.

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(2^k) = (4^k-4)/3 for k >= 2. - N. J. A. Sloane, Feb 13 2010.

CROSSREFS

Partial sums of A168131.

Sequence in context: A176848 A058615 A082612 * A122413 A297661 A136366

Adjacent sequences:  A170923 A170924 A170925 * A170927 A170928 A170929

KEYWORD

nonn

AUTHOR

Omar E. Pol. Jan 18 2010.

EXTENSIONS

Edited and extended by N. J. A. Sloane, Feb 01 2010

STATUS

approved

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Last modified January 18 23:05 EST 2019. Contains 319282 sequences. (Running on oeis4.)