A125541 Number of n X n arrays with entries in 1..9 in which adjacent entries differ by 6 or less (adjacent means in x or y directions).

1, 9, 4999, 183051647, 432993880473035, 66327998573151304476953, 657786158098403835519781868703261, 422337116619421509499034109697459735541947069

Offset

0,2

Comments

[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))

Links

Table of n, a(n) for n=0..7.

Prog

(S/R) stvar $[N][N]:(0.. M-1) init $[][]:=0 asgn $[][]->{*} kill +[i in 0.. N-2](+[j in 0.. N-1](($[i][j]`-$[i+1][j]`>6)+($[i+1][j]`-$[i][j]`>6)+($[j][i]`-$[j][i+1]`>6)+($[j][i+1]`-$[j][i]`>6)))

Crossrefs

Sequence in context: A216421 A323337 A167064 * A151581 A145263 A185821

Adjacent sequences: A125538 A125539 A125540 * A125542 A125543 A125544

Keyword

nonn

Author

R. H. Hardin, Dec 31 2006

Status

approved