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Search: id:A125531
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| A125531 |
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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). |
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+0
1
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| 1, 4, 54, 3682, 1209830, 1909172038, 14441437270426, 523308354987531254, 90815542491916256949262, 75466682574077698691682950866, 300268405527350796472180876929042538
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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[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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PROGRAM
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(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)))
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CROSSREFS
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Sequence in context: A111161 A003955 A094154 this_sequence A095209 A107101 A147780
Adjacent sequences: A125528 A125529 A125530 this_sequence A125532 A125533 A125534
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KEYWORD
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nonn
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AUTHOR
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Ron Hardin (rhhardin(AT)att.net), Dec 31 2006
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