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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). 0
1, 4, 54, 3682, 1209830, 1909172038, 14441437270426, 523308354987531254, 90815542491916256949262, 75466682574077698691682950866, 300268405527350796472180876929042538 (list; graph; refs; listen; history; text; internal format)
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: A094154 A168510 A324235 * A095209 A107101 A147780

Adjacent sequences:  A125528 A125529 A125530 * A125532 A125533 A125534

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 31 2006

STATUS

approved

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Last modified August 15 13:27 EDT 2020. Contains 336504 sequences. (Running on oeis4.)