%I
%S 2,26,506,11482,284002,7426610,201922730,5650739930,161686253810,
%T 4708709084026,139111173397066,4159013698117618,125595645802182818,
%U 3825428523179727266,117382025506323434506,3625185567639373456090
%N Number of permutations of n copies of 1..4 with all adjacent differences <= 1 in absolute value.
%H R. H. Hardin, <a href="/A177316/b177316.txt">Table of n, a(n) for n=1..31</a>
%K nonn
%O 1,1
%A _R. H. Hardin_ May 06 2010
