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A199649
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Number of n X 2 0..2 arrays with values 0..2 introduced in row major order and each element equal to no more than two horizontal and vertical neighbors.
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2
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2, 14, 113, 953, 8037, 67774, 571530, 4819638, 40643380, 342740340, 2890284724, 24373395288, 205537673480, 1733272476824, 14616461440144, 123258718919184, 1039424750772560, 8765333779162336, 73916920107029408, 623331776719986016
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OFFSET
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1,1
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COMMENTS
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Column 2 of A199655.
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..200
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FORMULA
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Empirical: a(n) = 8*a(n-1) + 4*a(n-2) - 2*a(n-3) - 8*a(n-4) for n>6.
Empirical g.f.: x*(2 - 2*x - 7*x^2 - 3*x^3 + 5*x^4 + 4*x^5) / (1 - 8*x - 4*x^2 + 2*x^3 + 8*x^4). - Colin Barker, Mar 02 2018
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EXAMPLE
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Some solutions for n=3:
..0..1....0..0....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..0
..0..2....1..1....2..2....0..1....1..2....2..0....0..1....2..2....0..2....1..0
..1..2....2..1....0..0....2..1....1..2....1..2....0..2....0..2....2..0....1..0
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CROSSREFS
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Cf. A199655.
Sequence in context: A214766 A330553 A275649 * A357584 A216581 A192406
Adjacent sequences: A199646 A199647 A199648 * A199650 A199651 A199652
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Nov 08 2011
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STATUS
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approved
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