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A242578 Number of length n+3 0..2 arrays with no four elements in a row with pattern aabb (with a!=b) and new values 0..2 introduced in 0..2 order. 1
13, 35, 97, 271, 757, 2115, 5913, 16535, 46237, 129291, 361537, 1010975, 2827013, 7905235, 22105577, 61814311, 172852717, 483351835, 1351607313, 3779529135, 10568780117, 29553711331, 82641690297, 231092768695, 646209770813 (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) = 4*a(n-1) - 5*a(n-2) + 6*a(n-3) - 4*a(n-4).

Empirical g.f.: x*(13 - 17*x + 22*x^2 - 20*x^3) / ((1 - x)*(1 - 3*x + 2*x^2 - 4*x^3)). - Colin Barker, Nov 01 2018

EXAMPLE

Some solutions for n=4:

..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0

..0....1....0....0....0....1....0....1....1....1....1....0....1....1....0....1

..1....2....1....1....1....0....0....2....0....1....1....1....1....0....1....1

..2....1....0....0....0....2....1....1....1....2....0....2....2....0....2....2

..1....0....2....0....1....0....0....1....0....0....1....1....1....2....0....1

..2....2....1....0....0....2....0....1....2....2....2....1....2....1....2....0

..1....1....1....0....1....2....1....1....0....1....0....2....1....0....2....2

CROSSREFS

Column 2 of A242584.

Sequence in context: A227986 A228024 A243383 * A192145 A221592 A135172

Adjacent sequences:  A242575 A242576 A242577 * A242579 A242580 A242581

KEYWORD

nonn

AUTHOR

R. H. Hardin, May 17 2014

STATUS

approved

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Last modified August 2 01:19 EDT 2021. Contains 346408 sequences. (Running on oeis4.)