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A205817 Number of (n+1) X 3 0..2 arrays with the number of clockwise edge increases in every 2 X 2 subblock unequal to the number of counterclockwise edge increases. 1
66, 216, 714, 2430, 8274, 28242, 96402, 329130, 1123698, 3836538, 13098738, 44721882, 152690034, 521316378, 1779885426, 6076908954, 20747864946, 70837641882, 241854837618, 825744066714, 2819266591602, 9625578232986 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A205823.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - a(n-2) - 4*a(n-3) + 2*a(n-4).

Empirical g.f.: 6*x*(11 - 8*x - 14*x^2 + 9*x^3) / ((1 - x)*(1 + x)*(1 - 4*x + 2*x^2)). - Colin Barker, Jun 12 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Cf. A205823.

Sequence in context: A202647 A202640 A074873 * A046393 A268582 A117306

Adjacent sequences:  A205814 A205815 A205816 * A205818 A205819 A205820

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 01 2012

STATUS

approved

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Last modified August 16 21:38 EDT 2022. Contains 356169 sequences. (Running on oeis4.)