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A269643
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Number of length-6 0..n arrays with no repeated value differing from the previous repeated value by other than plus two or minus 1.
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1
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16, 396, 2828, 12125, 38738, 101999, 234080, 484673, 926390, 1660883, 2825684, 4601765, 7221818, 10979255, 16237928, 23442569, 33129950, 45940763, 62632220, 84091373, 111349154, 145595135, 188193008, 240696785, 304867718, 382691939
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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) = n^6 + 6*n^5 + 5*n^4 + 12*n^3 - 12*n^2 + 9*n - 7 for n>2.
G.f.: x*(16 + 284*x + 392*x^2 + 85*x^3 - 49*x^4 + 2*x^5 - 14*x^6 + 5*x^7 - x^8) / (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>9.
(End)
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EXAMPLE
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Some solutions for n=3:
..1. .2. .3. .0. .2. .3. .1. .2. .1. .0. .0. .0. .1. .0. .1. .2
..2. .2. .1. .3. .0. .1. .0. .0. .1. .1. .1. .3. .2. .2. .3. .1
..2. .0. .2. .3. .0. .3. .3. .3. .0. .1. .0. .0. .0. .0. .2. .2
..3. .3. .3. .1. .1. .0. .1. .0. .2. .2. .3. .0. .2. .1. .1. .3
..2. .1. .2. .3. .3. .1. .0. .1. .0. .3. .0. .1. .1. .1. .3. .2
..1. .3. .2. .2. .1. .2. .1. .0. .2. .1. .3. .3. .0. .2. .3. .1
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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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