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A234825 Number of (n+1) X (1+1) 0..2 arrays with each 2 X 2 subblock having the number of clockwise edge increases less than or equal to the number of counterclockwise edge increases. 1
69, 516, 3843, 28602, 212850, 1583955, 11787201, 87715899, 652748544, 4857507711, 36147734568, 268997764212, 2001779586225, 14896486309185, 110854015040601, 824933638413864, 6138844024165119, 45682954601641506, 339955264040033718 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 9*a(n-1) - 12*a(n-2) + 3*a(n-3).

Empirical g.f.: 3*x*(23 - 35*x + 9*x^2) / (1 - 9*x + 12*x^2 - 3*x^3). - Colin Barker, Oct 16 2018

EXAMPLE

Some solutions for n=4:

..2..0....2..2....2..1....1..1....0..2....0..1....2..2....1..2....2..2....1..0

..2..0....1..2....2..2....0..0....2..1....0..0....1..1....2..0....0..1....1..2

..0..0....1..1....0..0....1..0....2..0....0..0....2..1....1..2....1..0....1..2

..1..2....2..1....1..1....1..1....0..2....1..1....0..2....2..2....1..2....2..1

..2..1....2..0....2..1....1..2....0..0....2..1....0..2....1..1....1..1....1..0

CROSSREFS

Column 1 of A234832.

Sequence in context: A253342 A253335 A234832 * A251010 A251003 A211692

Adjacent sequences:  A234822 A234823 A234824 * A234826 A234827 A234828

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 31 2013

STATUS

approved

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Last modified August 19 10:38 EDT 2022. Contains 356228 sequences. (Running on oeis4.)