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A221121 Number of n X 3 arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor. 1
8, 200, 4872, 118472, 2880520, 70036168, 1702839048, 41402332360, 1006644240392, 24475254623432, 595084206353160, 14468703925621448, 351787849605678088, 8553267228797150920, 207961646114893122312, 5056318842606537992392 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A221125.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..124

FORMULA

Empirical: a(n) = 26*a(n-1) - 41*a(n-2).

Conjectures from Colin Barker, Aug 03 2018: (Start)

G.f.: 8*x*(1 - x) / (1 - 26*x + 41*x^2).

a(n) = ((13-8*sqrt(2))^n*(4-7*sqrt(2)) + (4+7*sqrt(2))*(13+8*sqrt(2))^n) / 41.

(End)

EXAMPLE

Some solutions for n=3.

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

..0..4..0....2..1..0....0..2..0....2..1..0....1..2..0....1..2..0....1..1..0

..1..0..1....2..0..1....3..0..1....3..1..0....2..1..1....1..1..2....1..3..0

CROSSREFS

Cf. A221125.

Sequence in context: A229265 A323562 A034861 * A264124 A317631 A309904

Adjacent sequences:  A221118 A221119 A221120 * A221122 A221123 A221124

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 02 2013

STATUS

approved

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Last modified August 3 04:46 EDT 2021. Contains 346435 sequences. (Running on oeis4.)