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A303631
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Number of n X 3 0..1 arrays with every element unequal to 2 or 3 horizontally or vertically adjacent elements, with upper left element zero.
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1
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0, 1, 0, 1, 0, 3, 2, 9, 12, 33, 56, 129, 244, 523, 1034, 2153, 4336, 8921, 18104, 37065, 75456, 154171, 314266, 641569, 1308492, 2670345, 5447424, 11115417, 22677188, 46269875, 94401330, 192609073, 392973504, 801784337, 1635862800, 3337639217
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OFFSET
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1,6
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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) +a(n-4) -a(n-5).
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EXAMPLE
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All solutions for n=4:
..0..1..0
..1..0..1
..1..0..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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