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A221576
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Number of 0..n arrays of length 6 with each element differing from at least one neighbor by something other than 1.
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1
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10, 141, 1210, 5913, 20944, 59705, 145800, 317233, 631328, 1170369, 2047960, 3416105, 5473008, 8471593, 12728744, 18635265, 26666560, 37394033, 51497208, 69776569, 93167120, 122752665, 159780808, 205678673, 262069344, 330789025
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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) = 1*n^6 + 2*n^5 - 5*n^4 + 24*n^3 - 41*n^2 + 50*n - 31 for n>3.
G.f.: x*(10 + 71*x + 433*x^2 + 54*x^3 + 378*x^4 - 355*x^5 + 193*x^6 - 80*x^7 + 18*x^8 - 2*x^9) / (1 - x)^7.
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>10.
(End)
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EXAMPLE
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Some solutions for n=6:
..6....3....0....1....4....6....5....2....1....6....0....4....6....3....5....3
..1....0....6....3....4....4....1....4....3....3....0....1....6....0....1....5
..1....1....1....3....2....1....3....6....2....6....1....4....6....6....3....0
..4....4....2....6....4....4....0....3....2....1....4....2....3....4....3....6
..3....6....6....2....0....0....2....3....0....0....0....6....6....4....3....2
..0....4....6....2....2....3....6....0....5....3....6....0....6....2....5....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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