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A221870 Number of nX2 arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor, without consecutive moves in the same direction 1
1, 20, 162, 1442, 12688, 110720, 970828, 8489090, 74301713, 650080567, 5688284025, 49771429169, 435493321644, 3810502524152, 33341324878142, 291731631862014, 2552608002906241, 22334937934827800, 195427359369424289 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A221873

LINKS

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

FORMULA

Empirical: a(n) = 7*a(n-1) +27*a(n-2) -77*a(n-3) -247*a(n-4) +195*a(n-5) +277*a(n-6) -51*a(n-7) -32*a(n-8) +103*a(n-9) -78*a(n-10) +25*a(n-11) -4*a(n-12)

EXAMPLE

Some solutions for n=3

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

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

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

CROSSREFS

Sequence in context: A118676 A067534 A041768 * A289181 A056114 A281204

Adjacent sequences:  A221867 A221868 A221869 * A221871 A221872 A221873

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 28 2013

STATUS

approved

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Last modified March 22 01:06 EDT 2019. Contains 321406 sequences. (Running on oeis4.)