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A232922 Number of 3 X n 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally, diagonally or antidiagonally. 1
27, 54, 246, 912, 3612, 13992, 54600, 212544, 828048, 3225120, 12562464, 48931776, 190594944, 742387008, 2891677248, 11263389888, 43872104640, 170886518976, 665621195712, 2592665453760, 10098708106176, 39335543742144 (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) + 4*a(n-2) - 2*a(n-3) for n>4.

Empirical g.f.: 3*x*(9 - 9*x - 8*x^2 + 4*x^3) / (1 - 3*x - 4*x^2 + 2*x^3). - Colin Barker, Oct 06 2018

EXAMPLE

Some solutions for n=5:

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

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

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

CROSSREFS

Row 3 of A232920.

Sequence in context: A043323 A033903 A175806 * A181874 A042444 A042442

Adjacent sequences:  A232919 A232920 A232921 * A232923 A232924 A232925

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 02 2013

STATUS

approved

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Last modified December 14 05:17 EST 2018. Contains 318090 sequences. (Running on oeis4.)