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A260009
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Number of (n+2) X (2+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00000101 00010101 or 01010101.
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1
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49, 98, 252, 578, 1232, 2738, 6262, 14112, 31500, 70688, 159198, 357858, 803428, 1805000, 4056988, 9116450, 20482308, 46022418, 103415312, 232373682, 522131898, 1173216800, 2636206832, 5923508168, 13309979250, 29907242450, 67201004772
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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) = 2*a(n-1) + a(n-3) + 3*a(n-4) - 5*a(n-5) - a(n-6) - a(n-8) + a(n-9) for n>10.
Empirical g.f.: x*(49 + 56*x^2 + 25*x^3 - 169*x^4 - 27*x^5 - 9*x^6 - 20*x^7 + 33*x^8 - x^9) / ((1 - 2*x - x^2 + x^3)*(1 + x^2 - 2*x^4 - x^6)). - Colin Barker, Dec 27 2018
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EXAMPLE
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Some solutions for n=4:
..1..0..0..0....1..0..1..0....0..0..0..0....0..1..0..1....0..1..0..0
..0..1..0..0....0..1..0..1....0..0..0..1....0..0..1..0....1..0..1..0
..1..0..1..0....1..0..1..0....1..0..1..0....0..1..0..1....0..1..0..0
..0..1..0..1....0..1..0..1....0..1..0..1....1..0..1..0....1..0..1..0
..0..0..1..0....1..0..1..0....0..0..1..0....0..1..0..1....0..1..0..0
..0..0..0..1....0..1..0..1....0..0..0..1....1..0..0..0....0..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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