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%I #8 Nov 26 2012 11:53:51
%S 1,9,25,71,203,583,1679,4845,14001,40503,117263,339699,984515,2854281,
%T 8277153,24007543,69642819,202046535,586220911,1700972653,4935747673,
%U 14322646039,41562779655,120613013891,350017652003,1015758270153
%N Number of base 9 n-digit numbers with adjacent digits differing by one or less.
%C [Empirical] a(base,n)=a(base-1,n)+3^(n-1) for base>=n; a(base,n)=a(base-1,n)+3^(n-1)-2 when base=n-1
%F Empirical G.f.: -(2*x^5+13*x^4-4*x^3-15*x^2+4*x+1) / ((x-1)*(x^4+6*x^3+x^2-4*x+1)). [_Colin Barker_, Nov 26 2012]
%o (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>1)+($[i+1]`-$[i]`>1))
%K nonn,base
%O 0,2
%A _R. H. Hardin_, Dec 26 2006
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