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%I #4 Oct 15 2014 14:44:54
%S 2,6,24,120,718,4994,39556,351320,3456742,37314126,438366374,
%T 5567209930,75995663398,1109556555434,17252609166736,284620418911180,
%U 4965138989585412,91317809653363376,1765937111915469414
%N Number of length n arrays x(i), i=1..n with x(i) in 0..i and no value appearing more than 4 times
%C Column 4 of A248842
%H R. H. Hardin, <a href="/A248838/b248838.txt">Table of n, a(n) for n = 1..196</a>
%e Some solutions for n=6
%e ..0....1....1....1....0....0....1....0....0....1....0....1....1....0....1....1
%e ..0....2....2....0....0....2....0....2....2....0....2....1....1....2....0....1
%e ..3....2....2....0....2....2....3....2....0....3....1....0....2....2....1....3
%e ..3....0....3....3....3....2....1....2....0....0....0....4....0....1....0....0
%e ..0....5....0....2....2....1....2....2....4....3....2....0....5....4....1....1
%e ..3....4....5....1....6....5....5....5....6....2....1....1....5....4....0....2
%K nonn
%O 1,1
%A _R. H. Hardin_, Oct 15 2014
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