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A283094
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Number of n X 2 0..1 arrays with no 1 equal to more than one of its horizontal and vertical neighbors, with the exception of exactly two elements.
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2
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0, 0, 6, 28, 142, 606, 2458, 9520, 35678, 130398, 467036, 1645468, 5718204, 19641544, 66795854, 225191264, 753433522, 2503868506, 8271225942, 27176203312, 88858110366, 289261952058, 937867756728, 3029675945528, 9754050602424
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OFFSET
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1,3
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 6*a(n-1) -3*a(n-2) -28*a(n-3) +6*a(n-4) +66*a(n-5) +33*a(n-6) -36*a(n-7) -30*a(n-8) +6*a(n-9) +9*a(n-10) -a(n-12).
Empirical: G.f.: -2*x^3*(-3+4*x+4*x^2-3*x^3+2*x^4-x^5-x^6+x^7)/(x^4-3*x^2-2*x+1)^3. - R. J. Mathar, Mar 02 2017
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EXAMPLE
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Some solutions for n=4:
..0..1. .0..0. .1..1. .0..0. .1..1. .1..0. .1..0. .0..1. .0..0. .0..0
..0..1. .1..0. .1..0. .0..1. .0..1. .1..1. .1..1. .1..1. .1..0. .0..1
..1..1. .1..0. .0..1. .0..1. .0..1. .0..1. .1..0. .1..0. .1..1. .1..1
..0..0. .1..1. .1..1. .1..1. .1..0. .1..0. .1..0. .0..1. .0..1. .1..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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