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A221633
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Equals one maps: number of 2 X n binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal, diagonal and antidiagonal neighbors in a random 0..3 2 X n array.
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1
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1, 8, 37, 176, 787, 3480, 14865, 62064, 254463, 1032248, 4160093, 16707056, 66965547, 268146328, 1073157737, 4293797168, 17177516055, 68714775736, 274868469813, 1099492794416, 4398008728003, 17592110670488, 70368592998337
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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) = 6*a(n-1) - 3*a(n-2) - 32*a(n-3) + 45*a(n-4) + 30*a(n-5) - 77*a(n-6) + 12*a(n-7) + 36*a(n-8) - 16*a(n-9) for n>10.
Empirical g.f.: x*(1 + 2*x - 8*x^2 + 10*x^3 + 53*x^4 + 80*x^5 + 150*x^6 + 72*x^7 + 56*x^8 -32*x^9) / ((1 - x)^4*(1 + x)^2*(1 - 2*x)*(1 + 2*x)*(1 - 4*x)). - Colin Barker, Aug 10 2018
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EXAMPLE
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Some solutions for n=3:
..1..0..1....1..0..1....1..1..0....1..0..1....0..0..0....0..1..0....0..0..0
..1..1..0....0..0..0....1..1..0....1..0..0....0..0..0....0..0..1....0..1..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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