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Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, up, down, down, up, up
0

%I #3 Mar 31 2012 12:35:44

%S 1,6,90,2496,110760,7183476,640668497,75212295268,11244165636152,

%T 2085704995841392

%N Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, up, down, down, up, up

%K nonn

%O 1,2

%A _R. H. Hardin_ May 10 2010