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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.
2
8, 200, 4872, 118472, 2880520, 70036168, 1702839048, 41402332360, 1006644240392, 24475254623432, 595084206353160, 14468703925621448, 351787849605678088, 8553267228797150920, 207961646114893122312, 5056318842606537992392
OFFSET
1,1
COMMENTS
Column 3 of A221125.
LINKS
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 02 2013
STATUS
approved