A221329 - OEIS

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A221329

Number of 2 X n arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2.

1, 17, 119, 866, 6328, 46211, 337274, 2460918, 17953576, 130970758, 955393448, 6969190236, 50836821440, 370827923908, 2704988609708, 19731401249156, 143929610463264, 1049886222652688, 7658333144969252, 55863255070913284

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Row 2 of A221328.

LINKS

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

FORMULA

Empirical: a(n) = 11*a(n-1) - 27*a(n-2) - a(n-3) + 8*a(n-4) - 16*a(n-5) - 6*a(n-6) + 2*a(n-7) for n>9.

Empirical g.f.: x*(1 + 6*x - 41*x^2 + 17*x^3 + 24*x^4 - 16*x^5 + x^6 + 5*x^7 - x^8) / (1 - 11*x + 27*x^2 + x^3 - 8*x^4 + 16*x^5 + 6*x^6 - 2*x^7). - Colin Barker, Aug 05 2018

EXAMPLE

Some solutions for n=3:

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

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

CROSSREFS

Cf. A221328.

Sequence in context: A048714 A010823 A022709 * A196806 A094944 A274325

Adjacent sequences: A221326 A221327 A221328 * A221330 A221331 A221332

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 11 2013

STATUS

approved