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A269693
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Number of length-7 0..n arrays with no repeated value differing from the previous repeated value by plus or minus one modulo n+1.
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1
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66, 1347, 13168, 69405, 260616, 786079, 2031072, 4674393, 9831160, 19235931, 35471184, 62246197, 104731368, 169953015, 267253696, 408823089, 610304472, 891481843, 1277052720, 1797491661, 2490009544, 3399613647, 4580273568
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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^7 + 7*n^6 + 21*n^5 + 15*n^4 - 13*n^3 - 11*n^2 + 3*n + 1 for n>1.
G.f.: x*(66 + 819*x + 4240*x^2 - 1919*x^3 + 3268*x^4 - 2323*x^5 + 1184*x^6 - 337*x^7 + 42*x^8) / (1 - x)^8.
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>9.
(End)
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EXAMPLE
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Some solutions for n=3:
..1. .1. .0. .0. .3. .0. .3. .3. .3. .0. .0. .3. .0. .2. .0. .2
..3. .0. .3. .0. .1. .2. .1. .2. .0. .3. .3. .2. .3. .2. .1. .0
..2. .3. .2. .1. .2. .3. .3. .2. .2. .0. .2. .3. .2. .2. .0. .1
..3. .1. .3. .3. .3. .3. .0. .3. .2. .2. .2. .3. .3. .2. .0. .3
..2. .2. .2. .0. .1. .1. .1. .0. .0. .1. .2. .3. .1. .2. .2. .1
..3. .0. .3. .1. .2. .0. .1. .0. .1. .2. .3. .1. .3. .0. .0. .0
..0. .0. .2. .3. .1. .3. .3. .0. .2. .2. .2. .3. .3. .3. .0. .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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