A232059 - OEIS

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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.

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

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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 * A343889 A263711 A263697

Adjacent sequences: A232056 A232057 A232058 * A232060 A232061 A232062

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 17 2013

STATUS

approved