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A125537
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Number of n X n arrays with entries in 1..7 in which adjacent entries differ by 4 or less (adjacent means in x or y directions).
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0
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1, 7, 1527, 11721313, 3050388738539, 27037458180935427547, 8157016618633297682357104957, 83768469285967811192253950787571671419, 29282610870399702055320868574328652947738735891523
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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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))
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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]`-$[i+1][j]`>4)+($[i+1][j]`-$[i][j]`>4)+($[j][i]`-$[j][i+1]`>4)+($[j][i+1]`-$[j][i]`>4)))
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CROSSREFS
| Sequence in context: A145451 A144676 A191957 * A203012 A203697 A001424
Adjacent sequences: A125534 A125535 A125536 * A125538 A125539 A125540
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KEYWORD
| nonn
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AUTHOR
| R. H. Hardin (rhhardin(AT)att.net), Dec 31 2006
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