%I #3 Mar 31 2012 12:35:44
%S 1,20,1635,339708,143060850,106681715484,128573202886349,
%T 234439539245241093
%N Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, down, down, up, down, up
%K nonn
%O 1,2
%A _R. H. Hardin_ May 10 2010
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