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A221297 Number of n X 2 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor, with no occupancy greater than 2. 2
3, 19, 137, 1001, 7305, 53291, 388741, 2835697, 20685009, 150886255, 1100633309, 8028513089, 58563541437, 427188362291, 3116100301045, 22730208012457, 165804141741249, 1209448362939775, 8822248421700605, 64353360753783545 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A221303.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..113

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).

Empirical g.f.: x*(3 - 14*x + 9*x^2 + 10*x^3 - 12*x^4 - 4*x^5 + 2*x^6) / (1 - 11*x + 27*x^2 + x^3 - 8*x^4 + 16*x^5 + 6*x^6 - 2*x^7). - Colin Barker, Mar 14 2018

EXAMPLE

Some solutions for n=3:

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

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

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

CROSSREFS

Cf. A221303.

Sequence in context: A215852 A105797 A278189 * A138513 A321515 A094661

Adjacent sequences:  A221294 A221295 A221296 * A221298 A221299 A221300

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 09 2013

STATUS

approved

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Last modified August 19 06:48 EDT 2022. Contains 356216 sequences. (Running on oeis4.)