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A221201
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Number of 2 X n arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, with no occupancy greater than 2.
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1
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0, 9, 10, 196, 720, 6400, 34272, 242064, 1460368, 9610000, 60194160, 387459856, 2455717680, 15698085264, 99863349040, 636989149456, 4056917039280, 25859869267600, 164758872493872, 1049992515273744, 6690497356781488
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 7*a(n-1) + 14*a(n-2) - 126*a(n-3) + 504*a(n-5) - 224*a(n-6) - 448*a(n-7) + 256*a(n-8).
Empirical g.f.: x^2*(9 - 53*x + 342*x^3 - 124*x^4 - 448*x^5 + 256*x^6) / ((1 - 2*x)*(1 + 2*x)*(1 - 7*x + 4*x^2)*(1 - 14*x^2 + 16*x^4)). - Colin Barker, Aug 04 2018
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EXAMPLE
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Some solutions for n=3:
..1..2..1....0..2..0....0..2..1....0..2..0....0..2..2....2..2..0....1..2..0
..0..2..0....0..2..2....0..2..1....1..2..1....0..2..0....0..2..0....1..2..0
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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