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

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

%S 1,6,90,2510,112020,7307874,655845094,77496572328,11662893335890,

%T 2177988280932500

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

%K nonn

%O 1,2

%A _R. H. Hardin_ May 10 2010