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A301959
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Number of nX3 0..1 arrays with every element equal to 0, 1 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.
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1
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3, 6, 16, 40, 100, 252, 632, 1588, 3988, 10016, 25156, 63180, 158680, 398532, 1000932, 2513888, 6313748, 15857276, 39826296, 100025620, 251219060, 630948512, 1584656932, 3979940588, 9995808408, 25104944036, 63052250436, 158358699360
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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) +3*a(n-2) +2*a(n-3)
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EXAMPLE
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Some solutions for n=5
..0..1..0. .0..1..0. .0..0..1. .0..1..0. .0..1..0. .0..1..0. .0..0..1
..1..0..1. .1..0..1. .1..0..1. .0..1..0. .0..1..0. .0..0..0. .1..0..1
..1..1..1. .1..1..1. .1..1..1. .0..1..0. .0..1..1. .0..1..0. .0..1..0
..1..0..0. .1..0..1. .1..0..0. .0..1..1. .0..0..1. .0..1..0. .0..1..0
..1..1..0. .1..0..0. .1..1..0. .0..0..1. .1..0..1. .0..1..1. .0..1..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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