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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
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 01 2012
STATUS
approved

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Last modified July 18 06:54 EDT 2024. Contains 374377 sequences. (Running on oeis4.)