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Number of length-n 0..4 arrays connected end-around, with no sequence of L<n elements immediately followed by itself (periodic "squarefree").
0

%I #8 Dec 12 2015 01:47:56

%S 5,20,60,240,720,2940,10080,38640,140400,529440,1956900,7335840,

%T 27285180,101960040,380209980,1419732000

%N Number of length-n 0..4 arrays connected end-around, with no sequence of L<n elements immediately followed by itself (periodic "squarefree").

%C Column 4 of A215228.

%e Some solutions for n=8:

%e ..2....2....1....4....4....3....3....1....0....0....1....1....4....4....4....4

%e ..3....4....4....0....0....1....4....3....4....1....4....3....0....2....2....1

%e ..2....0....3....2....4....2....2....4....1....0....3....0....3....3....1....3

%e ..0....4....1....3....3....0....1....3....3....3....1....4....2....2....4....0

%e ..1....3....2....4....0....1....3....0....2....2....3....3....1....1....0....3

%e ..2....0....3....3....1....3....2....2....4....0....0....0....4....0....2....1

%e ..4....2....0....1....0....0....0....4....3....1....3....2....3....2....0....0

%e ..0....1....3....2....2....2....1....2....2....3....2....4....2....0....3....2

%K nonn,more

%O 1,1

%A _R. H. Hardin_, Aug 06 2012