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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

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

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

Adjacent sequences:  A206675 A206676 A206677 * A206679 A206680 A206681

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 11 2012

STATUS

approved

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Last modified August 5 06:46 EDT 2020. Contains 336209 sequences. (Running on oeis4.)