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A230814 Number of nX3 0..2 arrays x(i,j) with each element horizontally or vertically next to at least one element with value (x(i,j)+1) mod 3 and at least one element with value (x(i,j)-1) mod 3, and upper left element zero 1
0, 2, 4, 12, 100, 326, 2114, 9226, 47220, 233480, 1135788, 5678402, 27785526, 137642146, 678271020, 3346581344, 16519160048, 81474120774, 402103867046, 1983757394910, 9788422760352, 48296742499360, 238296850975076 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 3 of A230819

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 6*a(n-1) -2*a(n-2) -19*a(n-3) -a(n-4) +169*a(n-5) -607*a(n-6) +913*a(n-7) -1279*a(n-8) +2352*a(n-9) -3003*a(n-10) +3418*a(n-11) -2775*a(n-12) +1279*a(n-13) -676*a(n-14) +156*a(n-15) -4*a(n-16) -62*a(n-17) +60*a(n-18) -12*a(n-19)

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A228809 A326945 A309718 * A325502 A038791 A327563

Adjacent sequences:  A230811 A230812 A230813 * A230815 A230816 A230817

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 30 2013

STATUS

approved

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Last modified May 20 17:47 EDT 2022. Contains 353876 sequences. (Running on oeis4.)