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A241608
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Number of length n+2 0..2 arrays with no consecutive three elements summing to more than 2.
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1
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10, 20, 40, 76, 147, 287, 556, 1077, 2091, 4057, 7868, 15264, 29613, 57445, 111438, 216184, 419380, 813563, 1578253, 3061693, 5939450, 11522085, 22351978, 43361147, 84117349, 163181309, 316559417, 614101361, 1191310271, 2311051970, 4483266305
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = a(n-1) + a(n-2) + 2*a(n-3) - a(n-5) - a(n-6).
Empirical g.f.: x*(10 + 10*x + 10*x^2 - 4*x^3 - 9*x^4 - 6*x^5) / (1 - x - x^2 - 2*x^3 + x^5 + x^6). - Colin Barker, Oct 30 2018
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EXAMPLE
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Some solutions for n=5:
..1....0....2....0....1....2....2....1....0....1....1....0....1....1....1....0
..0....1....0....0....0....0....0....1....1....0....0....0....0....0....0....1
..1....0....0....0....1....0....0....0....0....1....1....0....1....0....0....0
..0....0....0....0....0....0....0....1....1....1....0....1....1....1....0....0
..0....2....0....0....0....1....0....1....1....0....0....0....0....0....1....0
..1....0....1....0....1....0....1....0....0....1....2....0....1....1....1....0
..1....0....0....2....0....0....1....0....0....0....0....2....1....0....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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