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A261374
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Number of (n+2) X (2+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00001011 00010101 or 01010101.
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1
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39, 41, 82, 157, 266, 470, 864, 1553, 2758, 4960, 8924, 16001, 28662, 51503, 92374, 165796, 297284, 533858, 957252, 1718645, 3081790, 5533474, 9922064, 17814980, 31944528, 57356546, 102846820, 184661677, 331120454, 594527399, 1066057422
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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-2) + 6*a(n-4) + 4*a(n-6) - a(n-8) for n > 9.
Empirical g.f.: x*(39 + 41*x + 43*x^2 + 116*x^3 - 50*x^4 + 67*x^5 - 50*x^6 - 23*x^7 + 9*x^8) / ((1 + x + 2*x^3 - x^4)*(1 - x - 2*x^3 - x^4)). - Colin Barker, Dec 30 2018
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EXAMPLE
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Some solutions for n=4:
0 1 0 1 0 0 1 0 1 0 0 1 0 1 0 0 1 0 0 0
1 0 1 0 0 0 0 1 1 0 0 0 1 0 0 0 0 1 0 1
0 1 0 1 1 0 1 0 0 1 0 1 0 1 0 1 1 0 1 0
1 0 1 0 0 1 0 1 1 0 1 0 1 0 1 0 0 0 0 1
0 1 0 1 0 0 1 0 0 1 0 1 0 1 0 0 0 0 1 0
1 0 1 0 0 1 0 1 1 0 0 0 0 0 1 0 1 1 0 1
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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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