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A231538
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Number of n X 2 0..1 arrays with no element less than a strict majority of its horizontal, vertical and antidiagonal neighbors.
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1
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2, 6, 20, 57, 164, 485, 1424, 4169, 12228, 35868, 105177, 308433, 904520, 2652574, 7778858, 22812126, 66898367, 196184665, 575326896, 1687191264, 4947820577, 14509871545, 42551335553, 124785126404, 365942162811, 1073154072467
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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) = 4*a(n-1) - 4*a(n-2) + 5*a(n-3) - 8*a(n-4) + 3*a(n-5) - 2*a(n-6) + a(n-7) - a(n-8).
Empirical g.f.: x*(2 - 2*x + 4*x^2 - 9*x^3 + 2*x^4 - x^5 + x^6 - x^7) / (1 - 4*x + 4*x^2 - 5*x^3 + 8*x^4 - 3*x^5 + 2*x^6 - x^7 + x^8). - Colin Barker, Sep 29 2018
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EXAMPLE
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Some solutions for n=7:
0 1 1 0 1 1 0 1 1 1 1 0 0 1 0 0 0 0 1 0
0 1 0 0 1 1 0 0 0 0 0 0 0 1 0 0 1 0 0 0
0 0 0 1 0 0 1 0 0 0 0 1 0 1 0 0 0 0 1 1
1 0 0 0 0 0 0 0 1 1 1 1 0 0 1 0 1 1 1 0
0 1 0 1 1 0 0 1 1 1 1 1 1 0 1 0 1 1 0 0
0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 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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