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A221595
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Number of 0..7 arrays of length n with each element differing from at least one neighbor by 1 or less.
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1
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0, 22, 62, 484, 2226, 13056, 67936, 374342, 2006006, 10894988, 58789204, 318224626, 1719926984, 9302621856, 50297494954, 271995651900, 1470758893578, 7953136851900, 43005796059376, 232551746953140, 1257506529312924
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 5*a(n-1) +3*a(n-2) -16*a(n-3) +65*a(n-4) -14*a(n-5) +23*a(n-6) +2*a(n-7) +8*a(n-8).
Empirical g.f.: 2*x^2*(11 - 24*x + 54*x^2 - 14*x^3 + 18*x^4 + 6*x^6) / (1 - 5*x - 3*x^2 + 16*x^3 - 65*x^4 + 14*x^5 - 23*x^6 - 2*x^7 - 8*x^8). - Colin Barker, Oct 19 2017
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EXAMPLE
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Some solutions for n=6
..7....3....0....2....5....0....6....2....3....3....4....6....5....6....6....6
..6....2....0....2....5....0....6....3....3....2....4....7....4....6....5....6
..5....4....0....7....3....1....6....7....5....3....3....4....6....0....7....1
..0....4....1....7....4....0....6....6....6....6....3....3....6....0....7....0
..1....5....3....0....0....3....7....4....5....6....2....2....2....5....2....5
..1....4....4....1....1....3....6....4....5....6....2....3....2....6....1....6
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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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