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A232059 Number of n X 2 0..2 arrays with every 0 next to a 1 and every 1 next to a 2 horizontally or vertically, with no adjacent values equal. 1
2, 6, 14, 30, 66, 146, 322, 710, 1566, 3454, 7618, 16802, 37058, 81734, 180270, 397598, 876930, 1934130, 4265858, 9408646, 20751422, 45768702, 100946050, 222643522, 491055746, 1083057542, 2388758606, 5268572958, 11620203458, 25629165522 (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) = 2*a(n-1) + a(n-3).

Empirical g.f.: 2*x*(1 + x + x^2) / (1 - 2*x - x^3). - Colin Barker, Oct 03 2018

EXAMPLE

Some solutions for n=7:

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

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

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

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

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

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

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

CROSSREFS

Column 2 of A232065.

Sequence in context: A000918 A059076 A237623 * A263711 A263697 A291409

Adjacent sequences:  A232056 A232057 A232058 * A232060 A232061 A232062

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 17 2013

STATUS

approved

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Last modified May 26 17:49 EDT 2019. Contains 323597 sequences. (Running on oeis4.)