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Search: id:A126515
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| A126515 |
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Number of base 20 n-digit numbers with adjacent digits differing by four or less. |
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+0
2
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| 1, 20, 160, 1320, 11000, 92172, 774696, 6522504, 54969166, 463511924, 3909629218, 32982588380, 278275931230, 2347955939840, 19811499262410, 167167589771462, 1410557938634156, 11902332555068524, 100432557218234836
(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 20 differing by three or less A126488, two or less A126407, one or less A126374.
Sequence in context: A120692 A059601 A125357 this_sequence A118676 A067534 A041768
Adjacent sequences: A126512 A126513 A126514 this_sequence A126516 A126517 A126518
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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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