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A261258
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Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010101 00100101 or 01010101.
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1
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36, 41, 91, 166, 321, 586, 1123, 2082, 3938, 7358, 13863, 25971, 48833, 91602, 172099, 323001, 606629, 1138805, 2138465, 4014874, 7538696, 14154181, 26576436, 49899170, 93691463, 175913869, 330296900, 620163290, 1164419552, 2186309750
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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) = a(n-1) + a(n-2) + 2*a(n-4) + a(n-6) for n>7.
Empirical g.f.: x*(36 + 5*x + 14*x^2 + 34*x^3 - 8*x^4 + 17*x^5 - 2*x^6) / (1 - x - x^2 - 2*x^4 - x^6). - Colin Barker, Dec 30 2018
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EXAMPLE
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Some solutions for n=4:
..1..0..0....0..1..0....0..1..0....1..0..1....0..1..0....1..0..0....1..0..0
..0..0..0....1..0..1....1..0..1....0..1..0....1..0..1....0..0..1....0..1..0
..1..0..1....0..0..0....0..1..0....0..1..0....0..0..0....1..0..0....1..0..1
..0..1..0....1..0..1....0..1..0....1..0..1....1..0..1....0..0..1....0..1..0
..1..0..1....0..1..0....1..0..1....0..1..0....0..1..0....1..0..0....0..0..1
..0..0..0....1..0..0....0..0..0....1..0..1....0..0..1....0..0..1....0..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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