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A221110
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Number of n X 4 arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, without 2-loops.
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1
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0, 7, 178, 3706, 73267, 1424745, 27551817, 531785885, 10257442136, 197807790635, 3814292012327, 73548334004184, 1418168141939766, 27345207646288006, 527271440369708686, 10166866164855156013, 196037839679146009768
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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) = 29*a(n-1) - 210*a(n-2) + 451*a(n-3) - 288*a(n-4) + 20*a(n-5) - a(n-6).
Empirical g.f.: x^2*(1 - 2*x)*(7 - 11*x - 8*x^2) / ((1 - x)*(1 - 28*x + 182*x^2 - 269*x^3 + 19*x^4 - x^5)). - Colin Barker, Aug 03 2018
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EXAMPLE
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Some solutions for n=3:
..0..2..2..1....0..1..0..0....0..2..2..0....0..1..2..1....0..1..1..1
..0..1..1..0....1..2..3..1....0..2..2..1....0..3..2..0....0..2..3..1
..1..2..2..0....0..2..2..0....1..1..1..0....1..1..1..0....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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