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 A269644 Number of length-7 0..n arrays with no repeated value differing from the previous repeated value by other than plus two or minus 1. 1
 20, 969, 9928, 55225, 216528, 675151, 1789528, 4200933, 8974480, 17780443, 33120936, 58606993, 99291088, 162060135, 256094008, 393394621, 589390608, 863622643, 1240514440, 1750234473, 2429653456, 3323402623, 4485037848 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = n^7 + 7*n^6 + 6*n^5 + 20*n^4 - 22*n^3 + 28*n^2 - 37*n + 13 for n>2. Conjectures from Colin Barker, Jan 25 2019: (Start) G.f.: x*(20 + 809*x + 2736*x^2 + 1813*x^3 - 152*x^4 - 31*x^5 - 240*x^6 + 123*x^7 - 44*x^8 + 6*x^9)  / (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>10. (End) EXAMPLE Some solutions for n=3: ..1. .3. .0. .2. .3. .1. .2. .3. .1. .0. .2. .1. .0. .0. .0. .0 ..2. .3. .3. .0. .1. .3. .0. .1. .1. .3. .3. .1. .3. .1. .1. .2 ..2. .0. .3. .1. .0. .2. .0. .3. .0. .2. .3. .2. .3. .0. .3. .3 ..1. .3. .2. .1. .3. .3. .2. .0. .3. .0. .2. .1. .1. .1. .1. .3 ..2. .2. .1. .0. .2. .1. .2. .1. .2. .3. .0. .0. .3. .0. .1. .0 ..1. .2. .0. .2. .3. .3. .1. .0. .0. .0. .1. .0. .2. .1. .2. .2 ..2. .1. .2. .1. .2. .2. .2. .1. .2. .3. .3. .1. .2. .3. .3. .1 CROSSREFS Row 7 of A269640. Sequence in context: A269413 A274764 A069578 * A347856 A128482 A128476 Adjacent sequences:  A269641 A269642 A269643 * A269645 A269646 A269647 KEYWORD nonn AUTHOR R. H. Hardin, Mar 02 2016 STATUS approved

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Last modified December 2 13:15 EST 2021. Contains 349444 sequences. (Running on oeis4.)