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A269532 Number of length-n 0..3 arrays with no repeated value differing from the previous repeated value by other than one. 2
4, 16, 60, 222, 804, 2878, 10192, 35812, 125012, 434110, 1500912, 5170626, 17758812, 60837880, 207965356, 709583398, 2417278172, 8223508510, 27943213944, 94853465148, 321696510276, 1090199408374, 3692112980824, 12496559933794 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 3 of A269537.
LINKS
FORMULA
Empirical: a(n) = 7*a(n-1) - 9*a(n-2) - 23*a(n-3) + 31*a(n-4) + 33*a(n-5).
Empirical g.f.: 2*x*(2 - 6*x - 8*x^2 + 19*x^3 + 17*x^4) / ((1 - 3*x)*(1 - 4*x - 3*x^2 + 14*x^3 + 11*x^4)). - Colin Barker, Mar 21 2018
EXAMPLE
Some solutions for n=9:
..2. .1. .0. .0. .3. .0. .1. .2. .1. .2. .0. .1. .1. .0. .0. .1
..1. .3. .3. .0. .0. .2. .2. .2. .0. .0. .3. .2. .3. .3. .2. .2
..0. .0. .2. .1. .3. .3. .0. .0. .3. .1. .0. .0. .1. .3. .0. .1
..2. .3. .2. .1. .2. .2. .1. .3. .1. .2. .0. .2. .0. .0. .3. .3
..2. .0. .3. .0. .0. .0. .0. .2. .0. .3. .2. .3. .3. .3. .2. .3
..3. .2. .0. .0. .3. .1. .0. .0. .2. .0. .3. .1. .3. .0. .0. .0
..1. .1. .3. .2. .2. .0. .3. .3. .2. .3. .2. .2. .1. .2. .1. .1
..1. .2. .0. .3. .3. .0. .1. .2. .0. .2. .1. .2. .2. .1. .2. .0
..3. .3. .3. .0. .0. .1. .3. .3. .3. .2. .2. .0. .2. .2. .1. .2
CROSSREFS
Cf. A269537.
Sequence in context: A268939 A269635 A267928 * A269673 A231896 A128650
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 29 2016
STATUS
approved

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Last modified April 14 16:12 EDT 2024. Contains 371665 sequences. (Running on oeis4.)