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Search: id:A124805
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| A124805 |
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Number of base 4 circular n-digit numbers with adjacent digits differing by 2 or less. |
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+0
1
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| 1, 4, 14, 46, 162, 574, 2042, 7270, 25890, 92206, 328394, 1169590, 4165554, 14835838, 52838618, 188187526, 670239810, 2387094478, 8501763050, 30279478102, 107841960402, 384084837406, 1367938433018, 4871984973862
(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)+A005191(n+1) for base>=2.int(n/2)+1
Sequence appears to have generating function (-1+x^2+4*x^3)/((1-x)*(2*x^2+3*x-1)). The degree of the numerator would drop by one if the initial term were changed from 1 to 3: (3-8*x+x^2)/((x-1)*(2*x^2+3*x-1)) - Creighton Dement (creighton.k.dement(AT)uni-oldenburg.de), Aug 20 2007
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PROGRAM
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(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>2)+($[(i+1)mod N]`-$[i]`>2))
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CROSSREFS
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Adjacent sequences: A124802 A124803 A124804 this_sequence A124806 A124807 A124808
Sequence in context: A027649 A049221 A081670 this_sequence A121530 A121299 A046718
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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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