A125530 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).

1, 3, 35, 2021, 536453, 661407975, 3780952160847, 100240477650720585, 12324646884990466825513, 7027467861520236770627093435, 18582989792598188051914777397933755

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..10.

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

Crossrefs

Sequence in context: A006098 A320845 A012499 * A334253 A068726 A263512

Adjacent sequences: A125527 A125528 A125529 * A125531 A125532 A125533

Keyword

nonn

Author

R. H. Hardin, Dec 31 2006

Status

approved