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A260602
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Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00000101 00010001 or 00010101.
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1
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40, 58, 125, 241, 525, 1029, 2246, 4407, 9592, 18930, 41027, 81192, 175502, 348438, 750714, 1494859, 3211981, 6412772, 13742956, 27507848, 58807987, 117983491, 251666242, 506004675, 1077074116, 2169965427, 4609962160, 9305093538
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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) + 2*a(n-2) - a(n-3) + 7*a(n-4) - 10*a(n-5) + 6*a(n-6) - 5*a(n-7) - 3*a(n-8) + 6*a(n-9) + 2*a(n-10) - 8*a(n-11) + 4*a(n-12) for n>13.
Empirical g.f.: x*(40 + 18*x - 13*x^2 + 40*x^3 - 188*x^4 + 141*x^5 - 127*x^6 + 43*x^7 + 117*x^8 - 70*x^9 - 110*x^10 + 136*x^11 - 36*x^12) / ((1 - x)*(1 - 2*x^2 - x^3 - 8*x^4 + 2*x^5 - 4*x^6 + x^7 + 4*x^8 - 2*x^9 - 4*x^10 + 4*x^11)). - Colin Barker, Dec 29 2018
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EXAMPLE
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Some solutions for n=4:
..1..0..0....0..0..1....0..0..0....0..1..0....1..0..0....0..0..0....1..0..1
..0..1..0....0..1..0....0..0..1....1..0..1....0..1..0....1..0..1....0..1..0
..1..0..0....0..0..1....0..1..0....0..0..0....0..0..1....0..1..0....1..0..0
..0..1..0....0..1..0....1..0..0....1..0..0....0..1..0....0..0..1....0..1..0
..0..0..1....1..0..1....0..1..0....0..1..0....0..0..1....0..0..0....0..0..1
..0..0..0....0..0..0....1..0..1....1..0..1....0..0..0....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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