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A277782
Number of n X 2 0..2 arrays with every element equal to some element at offset (-1,-1) (-1,0) (-1,1) (0,-1) (0,1) (1,-1) or (1,0) both plus 1 mod 3 and minus 1 mod 3, with new values introduced in order 0..2.
1
0, 3, 12, 84, 498, 3090, 18930, 116382, 714810, 4391526, 26977818, 165732438, 1018135578, 6254670486, 38424042426, 236048762550, 1450108129242, 8908386492054, 54726504918906, 336198967755510, 2065356559176474
OFFSET
1,2
LINKS
FORMULA
Empirical: a(n) = 5*a(n-1) +8*a(n-2) -6*a(n-3).
Empirical g.f.: 3*x^2*(1 - x) / (1 - 5*x - 8*x^2 + 6*x^3). - Colin Barker, Feb 06 2019
EXAMPLE
Some solutions for n=4:
..0..1. .0..1. .0..1. .0..1. .0..1. .0..1. .0..1. .0..1. .0..1. .0..1
..2..1. .2..0. .2..2. .2..1. .2..0. .2..0. .2..1. .2..0. .2..1. .2..2
..0..1. .1..1. .1..2. .0..1. .1..0. .0..2. .0..2. .1..0. .1..2. .0..2
..0..2. .0..2. .0..1. .2..2. .2..0. .1..2. .1..2. .2..1. .0..0. .1..2
CROSSREFS
Column 2 of A277788.
Sequence in context: A357846 A051549 A245775 * A066780 A328778 A231868
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 31 2016
STATUS
approved