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A268940
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Number of length-n 0..4 arrays with no repeated value unequal to the previous repeated value plus one mod 4+1.
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1
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5, 25, 120, 565, 2615, 11950, 54045, 242365, 1079240, 4777225, 21038595, 92244790, 402898865, 1753806625, 7611458520, 32945585965, 142262759615, 612991045150, 2636186279445, 11317111447765, 48506655275240, 207603081203425
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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) = 7*a(n-1) - 7*a(n-2) - 20*a(n-3).
Empirical g.f.: 5*x*(1 - 2*x - 4*x^2) / ((1 - 4*x)*(1 - 3*x - 5*x^2)). - Colin Barker, Jan 17 2019
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EXAMPLE
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Some solutions for n=7:
..2. .0. .3. .2. .2. .4. .1. .2. .3. .2. .2. .1. .1. .1. .3. .2
..3. .4. .3. .1. .3. .0. .3. .1. .3. .4. .0. .0. .2. .4. .0. .1
..1. .3. .0. .3. .2. .3. .1. .3. .2. .4. .3. .1. .4. .1. .2. .1
..3. .4. .1. .1. .0. .4. .4. .1. .1. .3. .2. .2. .1. .1. .1. .4
..4. .0. .4. .4. .0. .0. .1. .4. .4. .4. .0. .2. .2. .4. .4. .1
..0. .0. .0. .0. .1. .2. .3. .3. .1. .3. .4. .4. .4. .0. .2. .4
..1. .3. .2. .1. .4. .3. .4. .3. .4. .0. .1. .0. .0. .2. .2. .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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