A177610 - OEIS

%I #5 Sep 03 2022 23:09:48

%S 1,20,1596,320048,129324340,92116698310,105699012290844,

%T 183051978088671332

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

%K nonn

%O 1,2

%A _R. H. Hardin_, May 10 2010