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A232250 Number of (n+1) X (1+1) 0..2 arrays with every element both >= and <= some horizontal or antidiagonal neighbor. 2
9, 37, 163, 723, 3209, 14245, 63235, 280707, 1246089, 5531525, 24555043, 109002515, 483874057, 2147969733, 9535072003, 42327224963, 187895169801, 834087159397, 3702603905187, 16436262714579, 72962363498889, 323887892265317 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

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

Empirical g.f.: x*(9 + x - 3*x^2 - 3*x^3) / (1 - 4*x - 2*x^2 + x^4). - Colin Barker, Oct 03 2018

EXAMPLE

Some solutions for n=6:

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

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

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

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

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

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

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

CROSSREFS

Column 1 of A232257.

Sequence in context: A026620 A048878 A246315 * A201441 A183327 A199894

Adjacent sequences:  A232247 A232248 A232249 * A232251 A232252 A232253

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 21 2013

STATUS

approved

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Last modified January 24 00:05 EST 2022. Contains 350515 sequences. (Running on oeis4.)