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A269490
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Number of length-n 0..4 arrays with no repeated value differing from the previous repeated value by one.
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1
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5, 25, 125, 617, 3021, 14695, 71115, 342749, 1646513, 7888637, 37714065, 179987481, 857744605, 4082846423, 19415519707, 92255164553, 438075822317, 2079098651337, 9863010567565, 46772069428089, 221735120808989, 1050936378053663
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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) = 12*a(n-1) - 43*a(n-2) + 24*a(n-3) + 75*a(n-4) + 20*a(n-5) - a(n-6).
Empirical g.f.: x*(5 - 35*x + 40*x^2 + 72*x^3 + 17*x^4 - x^5) / (1 - 12*x + 43*x^2 - 24*x^3 - 75*x^4 - 20*x^5 + x^6). - Colin Barker, Jan 23 2019
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EXAMPLE
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Some solutions for n=6:
..4. .0. .2. .2. .3. .4. .2. .2. .0. .3. .0. .4. .2. .0. .2. .0
..2. .3. .0. .4. .2. .1. .1. .3. .4. .2. .0. .0. .4. .2. .0. .0
..0. .0. .4. .1. .1. .3. .4. .3. .0. .1. .0. .3. .4. .1. .0. .2
..3. .0. .2. .1. .2. .2. .1. .3. .1. .1. .0. .3. .3. .4. .3. .2
..0. .4. .3. .0. .1. .0. .3. .1. .1. .0. .3. .0. .4. .3. .0. .4
..1. .1. .2. .1. .4. .3. .1. .4. .0. .3. .1. .4. .0. .1. .0. .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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