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A197368
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Number of n X 3 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,4,1,0,1 for x=0,1,2,3,4.
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1
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1, 3, 32, 45, 189, 646, 1873, 6209, 19883, 62891, 201940, 644884, 2058462, 6580709, 21022103, 67159181, 214583759, 685563259, 2190314160, 6997940987, 22357818950, 71431546562, 228218559544, 729140737836, 2329549699706, 7442735684274
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OFFSET
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1,2
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COMMENTS
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Every 0 is next to 0 2's, every 1 is next to 1 4's, every 2 is next to 2 1's, every 3 is next to 3 0's, every 4 is next to 4 1's.
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LINKS
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FORMULA
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Empirical: a(n) = 2*a(n-1) +2*a(n-2) +7*a(n-3) -3*a(n-4) -7*a(n-6) -5*a(n-7) +3*a(n-8).
Empirical g.f.: x*(1 + x + 24*x^2 - 32*x^3 + 17*x^4 - 37*x^5 - 9*x^6 + 9*x^7) / (1 - 2*x - 2*x^2 - 7*x^3 + 3*x^4 + 7*x^6 + 5*x^7 - 3*x^8). - Colin Barker, May 12 2018
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EXAMPLE
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Some solutions for n=4:
..0..0..0....2..1..0....0..3..0....0..1..0....0..0..0....0..3..0....0..0..0
..0..0..0....1..4..1....3..0..0....1..4..1....3..0..0....0..0..3....3..0..3
..3..0..0....0..1..0....0..0..0....0..1..0....0..0..3....0..0..0....0..0..0
..0..3..0....0..0..0....0..3..0....0..0..0....0..3..0....0..0..0....0..3..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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