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A206678 Number of (n+1) X 2 0..2 arrays with every 2 X 3 or 3 X 2 subblock having an unequal number of clockwise and counterclockwise edge increases. 1
81, 306, 1404, 5352, 24336, 93696, 422016, 1639296, 7321728, 28666368, 127080960, 501063168, 2206534656, 8754665472, 38325454848, 152909291520, 665878216704, 2669887807488, 11572292272128, 46604992118784, 201163253317632 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 1 of A206685.
LINKS
FORMULA
Empirical: a(n) = 16*a(n-2) + 4*a(n-3) + 8*a(n-4).
Empirical g.f.: 3*x*(27 + 102*x + 36*x^2 + 44*x^3) / (1 - 16*x^2 - 4*x^3 - 8*x^4). - Colin Barker, Jun 17 2018
EXAMPLE
Some solutions for n=4:
..1..2....1..0....0..1....2..1....2..0....0..1....2..1....2..0....1..2....1..0
..1..1....1..1....1..1....1..2....1..2....2..1....0..2....1..2....1..0....0..2
..2..0....2..0....0..2....0..0....0..0....2..1....1..2....0..2....2..1....0..1
..1..2....2..2....1..0....1..0....1..1....2..0....2..1....1..0....0..0....2..0
..1..0....0..1....2..2....2..2....2..0....2..0....2..0....2..2....2..2....1..1
CROSSREFS
Cf. A206685.
Sequence in context: A206685 A206270 A236011 * A237463 A237456 A183994
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 11 2012
STATUS
approved

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Last modified April 22 11:51 EDT 2024. Contains 371898 sequences. (Running on oeis4.)