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A243383 Number of length n+3 0..2 arrays with no four elements in a row with pattern abba (with a!=b) and new values 0..2 introduced in 0..2 order. 1
13, 35, 96, 265, 733, 2029, 5618, 15557, 43081, 119303, 330384, 914929, 2533705, 7016569, 19430930, 53809925, 149015413, 412667243, 1142796240, 3164736889, 8764081669, 24270304357, 67211568290, 186128482181, 515444182609 (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) - 4*a(n-2) + 2*a(n-3) - a(n-4).

Empirical g.f.: x*(13 - 17*x + 8*x^2 - 5*x^3) / ((1 - x)*(1 - 3*x + x^2 - x^3)). - Colin Barker, Nov 02 2018

EXAMPLE

Some solutions for n=3:

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

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

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

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

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

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

CROSSREFS

Column 2 of A243389.

Sequence in context: A063300 A227986 A228024 * A242578 A192145 A221592

Adjacent sequences:  A243380 A243381 A243382 * A243384 A243385 A243386

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jun 04 2014

STATUS

approved

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Last modified January 27 13:38 EST 2022. Contains 350607 sequences. (Running on oeis4.)