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A278000 Number of n X 2 0..2 arrays with every element plus 1 mod 3 equal to some element at offset (-1,-1) (-1,0) (-1,1) (0,-1) (0,1) (1,-1) or (1,0), with upper left element zero. 1
0, 9, 52, 364, 2523, 17424, 120462, 832701, 5756112, 39789720, 275050323, 1901312388, 13143008754, 90852339501, 628025724756, 4341289537476, 30009590539371, 207444243598344, 1433978719090182, 9912518810524413 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

Empirical: a(n) = 6*a(n-1) + 6*a(n-2) + 3*a(n-3) - 6*a(n-4).

Empirical g.f.: x^2*(9 - 2*x - 2*x^2) / (1 - 6*x - 6*x^2 - 3*x^3 + 6*x^4). - Colin Barker, Feb 06 2019

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 2 of A278006.

Sequence in context: A289418 A292488 A282179 * A159598 A279358 A156544

Adjacent sequences:  A277997 A277998 A277999 * A278001 A278002 A278003

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 08 2016

STATUS

approved

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Last modified April 25 16:08 EDT 2019. Contains 322461 sequences. (Running on oeis4.)