A177600 - OEIS

%I #8 Jan 25 2016 15:51:39

%S 1,1,20,1680,354624,151213748,114062310060,139028830444866,

%T 256400413791435360,680598969845995094212,2500271405904975564019712

%N Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, down, down, down.

%Y Cf. A014606.

%K nonn

%O 0,3

%A _R. H. Hardin_, May 10 2010

%E a(9)-a(10) from _Alois P. Heinz_, Nov 02 2013