A177606 - OEIS

%I #5 Jan 25 2016 15:53:21

%S 1,1,20,1680,369600,167262000,135190246573,177591503329934,

%T 354324970027942152

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

%Y Cf. A014606.

%K nonn

%O 0,3

%A _R. H. Hardin_, May 10 2010