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A234029
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Number of (n+1) X (1+1) 0..4 arrays with every 2 X 2 subblock having the absolute values of all six edge and diagonal differences no larger than 1.
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1
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61, 307, 1543, 7783, 39331, 199003, 1007683, 5105107, 25871611, 131138323, 664800571, 3370454419, 17088658027, 86644639459, 439323545083, 2227578407827, 11294972125867, 57271642785859, 290399314134427, 1472490373513267
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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) = 7*a(n-1) - 6*a(n-2) - 18*a(n-3) - 6*a(n-4).
Empirical g.f.: x*(61 - 120*x - 240*x^2 - 78*x^3) / (1 - 7*x + 6*x^2 + 18*x^3 + 6*x^4). - Colin Barker, Oct 12 2018
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EXAMPLE
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Some solutions for n=5:
..4..4....3..4....3..3....4..4....0..1....2..2....3..2....1..2....1..2....1..2
..3..3....3..3....3..3....3..3....0..1....2..1....3..3....2..2....2..2....2..1
..2..2....3..2....4..3....3..3....1..1....1..1....3..2....2..2....3..3....1..1
..1..1....2..3....3..4....2..2....2..1....1..1....3..3....2..1....3..2....1..0
..1..0....3..3....3..4....3..3....2..2....2..1....3..3....1..2....2..2....1..1
..1..0....2..3....3..4....3..4....3..3....1..1....4..3....2..1....2..2....2..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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