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A126402
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Number of base 15 n-digit numbers with adjacent digits differing by two or less.
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3
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1, 15, 69, 325, 1543, 7361, 35223, 168899, 811105, 3899407, 18761375, 90319881, 434998065, 2095690739, 10098729091, 48672013183, 234609419433, 1130969299775, 5452365150693, 26286944474683, 126739125460983
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OFFSET
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0,2
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COMMENTS
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[Empirical] 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+6*x-46*x^2+14*x^3+102*x^4-25*x^5-52*x^6+5*x^7+2*x^8) / (1-9*x+20*x^2+10*x^3-46*x^4+x^5+23*x^6-x^7-x^8) (conjectured). - Colin Barker, Jul 18 2017
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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 15 differing by one or less A126369.
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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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