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%I #4 Feb 04 2016 21:59:02
%S 2,9,61,581,7160,108032,1926444,39616567,922677334,24000231919,
%T 689530024294,21683683196634,740776505063512,27318331535557441,
%U 1081605306266896792,45759587251345781091,2060162120919764963754
%N Number of length-n 0..n arrays with no adjacent pair x,x+1 followed at any distance by x+1,x.
%C Diagonal of A268457.
%e Some solutions for n=6
%e ..0....3....1....3....5....3....6....1....6....3....1....2....2....5....1....3
%e ..1....0....1....5....3....1....6....4....3....6....2....2....3....0....1....5
%e ..3....6....2....1....5....5....4....2....3....6....2....1....1....1....2....5
%e ..6....1....6....1....5....4....3....5....0....2....0....5....6....4....4....1
%e ..1....2....4....2....3....1....1....5....2....0....1....5....3....2....0....0
%e ..3....6....4....2....3....6....2....1....0....0....1....1....4....1....4....1
%Y Cf. A268457.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 04 2016