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Search: id:A126504
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| A126504 |
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Number of base 9 n-digit numbers with adjacent digits differing by four or less. |
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+0
2
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| 1, 9, 61, 429, 3011, 21141, 148433, 1042167, 7317185, 51374875, 360709449, 2532586341, 17781606753, 124846894103, 876565722303, 6154478019155, 43211363078111, 303392406838867, 2130156189729353, 14956094122197975
(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,n)=a(base-1,n)+9^(n-1) for base>=4n-3; a(base,n)=a(base-1,n)+9^(n-1)-2 when base=4n-4
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PROGRAM
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(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>4)+($[i+1]`-$[i]`>4))
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CROSSREFS
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Cf. Base 9 differing by three or less A126477, two or less A126396, one or less A126363.
Sequence in context: A125346 A016200 A001454 this_sequence A025014 A075139 A098921
Adjacent sequences: A126501 A126502 A126503 this_sequence A126505 A126506 A126507
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KEYWORD
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nonn
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AUTHOR
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Ron Hardin (rhh(AT)cadence.com), Dec 28 2006
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