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A269469
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Number of length-5 0..n arrays with no repeated value equal to the previous repeated value.
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1
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14, 174, 852, 2780, 7170, 15834, 31304, 56952, 97110, 157190, 243804, 364884, 529802, 749490, 1036560, 1405424, 1872414, 2455902, 3176420, 4056780, 5122194, 6400394, 7921752, 9719400, 11829350, 14290614, 17145324, 20438852, 24219930
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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^5 + 5*n^4 + 7*n^3 + 2*n^2 - n.
G.f.: 2*x*(7 + 45*x + 9*x^2 - x^3) / (1 - x)^6.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6.
(End)
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EXAMPLE
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Some solutions for n=3:
..0. .1. .1. .3. .3. .2. .0. .3. .2. .2. .0. .3. .3. .2. .1. .1
..3. .1. .3. .2. .3. .2. .3. .1. .0. .1. .1. .3. .2. .3. .2. .3
..1. .2. .0. .3. .0. .1. .1. .3. .0. .0. .3. .0. .2. .2. .1. .2
..0. .2. .3. .0. .3. .3. .2. .2. .1. .0. .3. .1. .1. .3. .2. .1
..3. .0. .3. .2. .2. .3. .3. .2. .1. .2. .0. .2. .0. .3. .2. .3
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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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