A125537 - OEIS

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

%S 1,7,1527,11721313,3050388738539,27037458180935427547,

%T 8157016618633297682357104957,83768469285967811192253950787571671419,

%U 29282610870399702055320868574328652947738735891523

%N Number of n X n arrays with entries in 1..7 in which adjacent entries differ by 4 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]`-$[i+1][j]`>4)+($[i+1][j]`-$[i][j]`>4)+($[j][i]`-$[j][i+1]`>4)+($[j][i+1]`-$[j][i]`>4)))

%K nonn

%O 0,2

%A _R. H. Hardin_, Dec 31 2006