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A218422
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Hilltop maps: number of nX4 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal, vertical or antidiagonal neighbor in a random 0..1 nX4 array
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1
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9, 191, 2725, 41515, 629659, 9539915, 144597047, 2191517757, 33214850067, 503408006597, 7629705089721, 115636627121941, 1752601092641329, 26562609636801375, 402585753260380041, 6101632743611966643
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 9*a(n-1) +72*a(n-2) +284*a(n-3) +526*a(n-4) +890*a(n-5) +902*a(n-6) +1382*a(n-7) -553*a(n-8) +2141*a(n-9) -1904*a(n-10) +416*a(n-11) -53*a(n-12) -263*a(n-13) -38*a(n-14) +38*a(n-15) -6*a(n-16) -18*a(n-17) +16*a(n-18) -a(n-20) +a(n-21)
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EXAMPLE
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Some solutions for n=3
..1..1..0..0....1..1..0..1....0..1..0..1....1..1..0..0....0..1..0..1
..1..0..1..0....0..1..1..1....1..1..1..1....1..0..1..1....1..0..0..1
..1..1..0..1....0..1..0..0....0..0..1..1....1..0..1..1....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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