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A266019
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Number of nX2 integer arrays with each element equal to the number of horizontal, vertical and antidiagonal neighbors exactly one smaller than itself.
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1
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3, 7, 14, 42, 99, 259, 719, 1784, 4792, 12479, 32263, 86025, 222663, 585072, 1535472, 4002444, 10527738, 27516774, 72060109, 188952481, 494214824, 1295507675, 3392305134, 8882420053, 23272852966, 60933892273, 159611564865, 418043981246
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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) = a(n-1) +2*a(n-2) +6*a(n-3) -a(n-4) +20*a(n-5) -25*a(n-6) -37*a(n-7) -53*a(n-8) -52*a(n-9) +47*a(n-10) +74*a(n-11) +77*a(n-12) +30*a(n-13) -29*a(n-14) -34*a(n-15) -34*a(n-16) -a(n-17) -6*a(n-18) +11*a(n-19) +a(n-20) +a(n-21)
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EXAMPLE
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Some solutions for n=4
..1..1....0..1....1..0....0..1....1..0....1..0....0..1....1..0....1..0....1..0
..0..1....1..2....1..1....2..1....1..2....1..1....2..1....1..2....1..2....2..1
..1..1....2..0....1..2....0..2....2..1....2..2....2..0....1..0....1..2....2..1
..2..0....1..1....0..0....0..1....0..1....0..1....1..1....1..1....0..1....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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