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A234780 Number of (n+1) X (2+1) 0..3 arrays with no adjacent elements equal and with each 2 X 2 subblock having the number of clockwise edge increases equal to the number of counterclockwise edge increases. 1
484, 6660, 91916, 1269036, 17521780, 241927524, 3340355564, 46121153580, 636806710036, 8792555155236, 121401086008460, 1676216233423404, 23143951620064564, 319554533544992100, 4412172198832106156 (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) = 16*a(n-1) - 31*a(n-2) + 10*a(n-3).

Empirical g.f.: 4*x*(121 - 271*x + 90*x^2) / (1 - 16*x + 31*x^2 - 10*x^3). - Colin Barker, Oct 16 2018

EXAMPLE

Some solutions for n=3:

..3..1..3....1..2..3....1..0..3....0..2..3....1..3..0....1..2..3....1..3..1

..2..3..2....2..3..2....0..2..0....3..0..2....0..1..2....3..1..2....3..1..0

..3..1..3....0..2..0....3..0..3....0..1..0....2..0..1....2..3..1....2..0..3

..1..0..1....2..3..2....1..2..0....2..3..2....0..2..3....3..0..3....3..2..0

CROSSREFS

Column 2 of A234786.

Sequence in context: A237078 A085120 A250614 * A013771 A114774 A013903

Adjacent sequences:  A234777 A234778 A234779 * A234781 A234782 A234783

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 30 2013

STATUS

approved

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Last modified September 17 10:37 EDT 2019. Contains 327129 sequences. (Running on oeis4.)