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A218191
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Hilltop maps: number of nX3 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or vertical neighbor in a random 0..3 nX3 array
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1
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7, 63, 507, 4067, 32529, 260205, 2081511, 16651157, 133202247, 1065561647, 8524042607, 68188735807, 545481047051, 4363617673705, 34907095864651, 279242003501369, 2233817926927103, 17869598656697015, 142949231583388401
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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) = 7*a(n-1) +7*a(n-2) +7*a(n-3) +6*a(n-4) +12*a(n-5) +10*a(n-6) +48*a(n-7) +9*a(n-8) +9*a(n-9) +9*a(n-10) +5*a(n-11) +13*a(n-12) +11*a(n-13) -52*a(n-14) -64*a(n-15) -63*a(n-16) -59*a(n-17) -48*a(n-18) -38*a(n-19) +13*a(n-20) +41*a(n-21) +48*a(n-22) +46*a(n-23) +33*a(n-24) +15*a(n-25) +5*a(n-26) -5*a(n-27) -7*a(n-28) -7*a(n-29) -6*a(n-30) -2*a(n-31) +2*a(n-32) -a(n-34) -a(n-35) -a(n-36) -a(n-37)
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EXAMPLE
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Some solutions for n=3
..1..1..0....0..1..0....1..0..0....0..0..0....0..1..1....1..0..0....1..0..0
..1..1..0....0..0..1....1..0..0....1..0..0....0..0..1....0..1..1....0..0..1
..0..0..0....0..1..0....0..0..1....1..1..1....0..1..0....0..0..1....0..0..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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