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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
OFFSET
1,1
LINKS
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 * A306761 A181874 A042444
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 02 2013
STATUS
approved