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A231213 Number of (n+1) X (2+1) 0..2 arrays with no element unequal to a strict majority of its horizontal and vertical neighbors, with values 0..2 introduced in row major order. 1
4, 9, 22, 59, 156, 413, 1098, 2919, 7760, 20633, 54862, 145875, 387876, 1031349, 2742322, 7291743, 19388504, 51553393, 137078774, 364487947, 969161452, 2576968397, 6852074138, 18219439575, 48444890080, 128813368009, 342510505246 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) - a(n-2) + a(n-3) - 2*a(n-4).
Empirical g.f.: x*(4 - 3*x - x^2 - 2*x^3) / ((1 - x)*(1 - 2*x - x^2 - 2*x^3)). - Colin Barker, Sep 27 2018
EXAMPLE
Some solutions for n=4:
..0..1..1....0..0..0....0..0..1....0..0..1....0..1..1....0..0..0....0..0..1
..0..1..1....0..0..0....0..0..1....0..0..1....0..1..1....1..1..0....0..0..1
..0..2..2....0..0..0....0..0..1....0..1..1....0..1..1....1..1..0....2..2..1
..0..2..2....0..0..0....0..1..1....0..1..1....0..0..1....1..1..0....2..2..1
..0..2..2....0..0..0....0..1..1....0..0..0....0..0..1....1..1..0....2..2..1
CROSSREFS
Column 2 of A231219.
Sequence in context: A318817 A122626 A135025 * A231338 A257272 A370021
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 05 2013
STATUS
approved

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Last modified February 26 21:28 EST 2024. Contains 370352 sequences. (Running on oeis4.)