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A219080
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Hilltop maps: number of 3 X n binary arrays indicating the locations of corresponding elements not exceeded by any horizontal, diagonal or antidiagonal neighbor in a random 0..1 3 X n array.
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1
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1, 41, 337, 2321, 17537, 134809, 1023441, 7759553, 58921537, 447447561, 3397273553, 25794057969, 195847550081, 1487017265657, 11290490704977, 85725445999521, 650888811968321, 4942012485147241, 37523285458920273
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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) + 5*a(n-2) + 46*a(n-3) + 61*a(n-4) - 10*a(n-5) - a(n-6) - 10*a(n-7).
Empirical g.f.: x*(1 + 35*x + 86*x^2 + 48*x^3 - 21*x^4 - 11*x^5 - 10*x^6) / (1 - 6*x - 5*x^2 - 46*x^3 - 61*x^4 + 10*x^5 + x^6 + 10*x^7). - Colin Barker, Jul 25 2018
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EXAMPLE
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Some solutions for n=3:
..1..1..0....0..1..1....0..1..1....1..1..1....1..1..1....0..1..0....0..1..0
..0..1..0....0..1..1....1..1..0....1..1..1....0..0..0....0..0..1....1..1..0
..0..0..1....0..1..0....1..0..0....0..0..1....0..1..1....0..1..1....1..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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