%I #6 Nov 02 2013 20:43:58
%S 1,20,1477,263978,93489715,57920130894,57577729726875,
%T 86198179666698834,185132216218421052414,548986840452318863546904
%N Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, down, down, up.
%K nonn
%O 1,2
%A _R. H. Hardin_, May 10 2010
%E a(9)-a(10) from _Alois P. Heinz_, Nov 02 2013