A125531 Number of n X n arrays with entries in 1..4 in which adjacent entries differ by 1 or less (adjacent means in x or y directions).

1, 4, 54, 3682, 1209830, 1909172038, 14441437270426, 523308354987531254, 90815542491916256949262, 75466682574077698691682950866, 300268405527350796472180876929042538

Offset: 0

Author

R. H. Hardin, Dec 31 2006

Keywords

• nonn

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))