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A221751
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Number of nX4 arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, without move-in move-out straight through or left turns
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0
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1, 9, 43, 241, 1397, 7989, 45956, 264378, 1520571, 8746983, 50315631, 289432219, 1664916443, 9577180972, 55091295173, 316904423483, 1822945187570
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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) = 5*a(n-1) +5*a(n-2) +a(n-3) -27*a(n-4) -7*a(n-5) +7*a(n-6) +2*a(n-7) -a(n-8)
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EXAMPLE
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Some solutions for n=3
..0..2..1..1....0..2..0..2....0..2..1..1....0..2..0..1....1..1..1..1
..1..1..1..1....1..1..2..0....1..1..1..1....1..1..2..1....0..2..1..1
..2..0..1..1....2..0..1..1....1..1..2..0....1..1..2..0....2..0..1..1
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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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