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A266028
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Number of n X 3 integer arrays with each element equal to the number of horizontal and antidiagonal neighbors less than itself.
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1
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5, 50, 481, 4659, 45361, 440405, 4281953, 41605113, 404371841, 3929676961, 38190819553, 371149900881, 3606990493057, 35054056081937, 340669003487777, 3310750747302897, 32175148917943745, 312690400948679185
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 5*a(n-1) + 46*a(n-2) + 6*a(n-3) - 72*a(n-4).
Empirical g.f.: x*(1 + 4*x)*(5 + 5*x - 19*x^2) / (1 - 5*x - 46*x^2 - 6*x^3 + 72*x^4). - Colin Barker, Jan 09 2019
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EXAMPLE
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Some solutions for n=4:
..0..0..1....0..0..0....0..0..1....0..1..2....1..0..2....0..0..0....0..0..2
..0..1..1....1..1..2....1..1..0....2..0..0....0..0..0....2..1..1....1..1..0
..1..0..0....2..0..2....1..0..2....0..0..2....0..0..1....2..0..2....2..0..0
..2..0..0....2..0..0....2..0..0....0..0..1....1..3..0....2..1..0....0..0..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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