A125532 Number of n X n arrays with entries in 1..4 in which adjacent entries differ by 2 or less (adjacent means in x or y directions).

1, 4, 162, 75398, 386994338, 22039625597766, 13914188992963436802, 97391265572623379728784646, 7557580190940015054807296049439074, 6502004785230840000033839573162175747164038

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..9.

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]`-$[i+1][j]`>2)+($[i+1][j]`-$[i][j]`>2)+($[j][i]`-$[j][i+1]`>2)+($[j][i+1]`-$[j][i]`>2)))

Crossrefs

Sequence in context: A041779 A222394 A306350 * A229405 A211157 A185857

Adjacent sequences: A125529 A125530 A125531 * A125533 A125534 A125535

Keyword

nonn

Author

R. H. Hardin, Dec 31 2006

Status

approved