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

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

%S 1,6,90,2518,113052,7434180,673334112,80360724360,12221802614520,

%T 2307379944600182

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

%K nonn

%O 1,2

%A _R. H. Hardin_ May 10 2010