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A215224 Number of length-n 0..4 arrays connected end-around, with no sequence of L<n elements immediately followed by itself (periodic "squarefree"). 0
5, 20, 60, 240, 720, 2940, 10080, 38640, 140400, 529440, 1956900, 7335840, 27285180, 101960040, 380209980, 1419732000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A215228.

LINKS

Table of n, a(n) for n=1..16.

EXAMPLE

Some solutions for n=8:

..2....2....1....4....4....3....3....1....0....0....1....1....4....4....4....4

..3....4....4....0....0....1....4....3....4....1....4....3....0....2....2....1

..2....0....3....2....4....2....2....4....1....0....3....0....3....3....1....3

..0....4....1....3....3....0....1....3....3....3....1....4....2....2....4....0

..1....3....2....4....0....1....3....0....2....2....3....3....1....1....0....3

..2....0....3....3....1....3....2....2....4....0....0....0....4....0....2....1

..4....2....0....1....0....0....0....4....3....1....3....2....3....2....0....0

..0....1....3....2....2....2....1....2....2....3....2....4....2....0....3....2

CROSSREFS

Sequence in context: A319869 A038165 A327383 * A270939 A270631 A032340

Adjacent sequences:  A215221 A215222 A215223 * A215225 A215226 A215227

KEYWORD

nonn,more

AUTHOR

R. H. Hardin, Aug 06 2012

STATUS

approved

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Last modified September 27 15:21 EDT 2020. Contains 337383 sequences. (Running on oeis4.)