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A219422
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Unchanging value maps: number of 2 X n binary arrays indicating the locations of corresponding elements unequal to no horizontal or antidiagonal neighbor in a random 0..2 2 X n array.
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1
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1, 7, 20, 57, 160, 454, 1292, 3676, 10452, 29724, 84548, 240480, 683968, 1945348, 5533040, 15737260, 44760324, 127308564, 362094824, 1029880752, 2929216636, 8331363064, 23696305892, 67397723860, 191694568548, 545223274608
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 2*a(n-1) + a(n-2) + 3*a(n-3) + 4*a(n-4) - 2*a(n-5) - 4*a(n-6) for n>8.
Empirical g.f.: x*(1 + 5*x + 5*x^2 + 7*x^3 + x^4 - 9*x^5 - 9*x^6 - 2*x^7) / ((1 + 2*x^2)*(1 - 2*x - 3*x^2 + x^3 + 2*x^4)). - Colin Barker, Jul 26 2018
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EXAMPLE
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Some solutions for n=3:
..0..0..0....1..0..1....0..0..1....0..0..0....1..0..0....0..0..1....0..0..0
..1..0..1....0..0..0....0..0..1....0..0..1....0..0..1....0..0..0....1..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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