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A126394
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Number of base 7 n-digit numbers with adjacent digits differing by two or less.
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3
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1, 7, 29, 125, 543, 2363, 10287, 44787, 194995, 848979, 3696331, 16093291, 70067867, 305065387, 1328210699, 5782837835, 25177641963, 109619822123, 477268896747, 2077959947307, 9047137938475, 39389933855019
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OFFSET
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0,2
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COMMENTS
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a(base,n)=a(base-1,n)+5^(n-1) for base>=2n-1; a(base,n)=a(base-1,n)+5^(n-1)-2 when base=2n-2.
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LINKS
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FORMULA
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G.f.: 1 -x*(7-6*x-6*x^2+4*x^3) / ( (x-1)*(2*x^3-2*x^2-4*x+1) ). - R. J. Mathar, Jun 06 2013
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PROG
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(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>2)+($[i+1]`-$[i]`>2))
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CROSSREFS
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Cf. Base 7 differing by one or less A126361.
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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