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A221324
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Number of n X 4 arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2.
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1
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17, 866, 46105, 2460824, 131347807, 7010554450, 374176705928, 19970973695923, 1065911268786396, 56890876705125765, 3036435876484206258, 162063633563069131638, 8649818983278197229631, 461666606875092805859284
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 91*a(n-1) -2497*a(n-2) +29072*a(n-3) -168762*a(n-4) +513070*a(n-5) -765950*a(n-6) +359339*a(n-7) +283374*a(n-8) -252113*a(n-9) -12688*a(n-10) +38079*a(n-11) -6354*a(n-12) +289*a(n-13).
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EXAMPLE
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Some solutions for n=3:
..1..1..2..1....0..1..0..1....0..2..1..2....0..2..2..2....2..1..1..0
..0..0..1..2....1..2..2..2....0..0..2..0....1..0..1..2....2..0..1..1
..1..0..2..1....2..0..0..1....2..0..1..2....1..0..1..0....1..2..1..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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