%I #6 Mar 31 2012 12:35:05

%S 1,3,35,2021,536453,661407975,3780952160847,100240477650720585,

%T 12324646884990466825513,7027467861520236770627093435,

%U 18582989792598188051914777397933755

%N Number of n X n arrays with entries in 1..3 in which adjacent entries differ by 1 or less (adjacent means in x or y directions).

%C [Empirical] a(base+1,n,diff)=a(base,n,diff)+F(n,diff) for base>=2.diff.(n-1) and F(n,diff)= (n=2, A063496(diff+1)) (n=3, A068744(diff+1)) (n=4, A068745(diff+1)) (n=5, A068746(diff+1)) (n=6, A068747(diff+1))

%o (S/R) stvar $[N][N]:(0.. M-1) init $[][]:=0 asgn $[][]->{*} kill +[i in 0.. N-2](+[j in 0.. N-1](($[i][j]`-$[i+1][j]`>1)+($[i+1][j]`-$[i][j]`>1)+($[j][i]`-$[j][i+1]`>1)+($[j][i+1]`-$[j][i]`>1)))

%K nonn

%O 0,2

%A _R. H. Hardin_, Dec 31 2006