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A269621
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Number of length-5 0..n arrays with no repeated value differing from the previous repeated value by other than plus two, zero or minus 1.
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1
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28, 222, 954, 2956, 7440, 16218, 31822, 57624, 97956, 158230, 245058, 366372, 531544, 751506, 1038870, 1408048, 1875372, 2459214, 3180106, 4060860, 5126688, 6405322, 7927134, 9725256, 11835700, 14297478, 17152722, 20446804, 24228456
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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 + 12*n^2 + 3*n.
G.f.: 2*x*(14 + 27*x + 21*x^2 + x^3 - 3*x^4) / (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=8:
..5. .0. .5. .4. .4. .7. .7. .8. .0. .1. .1. .3. .6. .0. .2. .3
..4. .1. .0. .6. .8. .8. .6. .3. .8. .5. .5. .8. .5. .4. .0. .5
..5. .2. .7. .5. .3. .0. .0. .4. .6. .3. .6. .0. .7. .5. .4. .4
..5. .0. .7. .6. .2. .6. .4. .0. .7. .0. .8. .1. .2. .0. .2. .4
..7. .1. .4. .6. .1. .6. .5. .8. .7. .6. .1. .2. .7. .4. .3. .5
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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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