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A233726 Number of (n+1) X (1+1) 0..3 arrays with every 2 X 2 subblock having the sum of the absolute values of the edge differences equal to 6 and no adjacent elements equal. 1
40, 148, 556, 2104, 7976, 30260, 114820, 435720, 1653488, 6274804, 23812172, 90364680, 342924296, 1301361476, 4938528804, 18741194360, 71120848176, 269896091748, 1024227097996, 3886833426776, 14750121431720, 55975149559572 (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) = 3*a(n-1) + 5*a(n-2) - 7*a(n-3) - 2*a(n-4).

Empirical g.f.: 4*x*(10 + 7*x - 22*x^2 - 6*x^3) / (1 - 3*x - 5*x^2 + 7*x^3 + 2*x^4). - Colin Barker, Oct 11 2018

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

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

CROSSREFS

Column 1 of A233733.

Sequence in context: A044753 A160148 A233733 * A100766 A189541 A201233

Adjacent sequences:  A233723 A233724 A233725 * A233727 A233728 A233729

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 15 2013

STATUS

approved

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Last modified July 25 10:56 EDT 2021. Contains 346289 sequences. (Running on oeis4.)