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%I #13 May 03 2023 17:59:26
%S 1,9,61,369,2501,17259,120367,842739,5910189,41476599,291156071,
%T 2044081081,14351282807,100760813695,707450453645,4967087326989,
%U 34874511797933,244858234557953,1719180148930309,12070578961004535
%N Number of base 9 circular n-digit numbers with adjacent digits differing by 4 or less.
%C [Empirical] a(base,n)=a(base-1,n)+A025014(n+1) for base>=4.int(n/2)+1
%F G.f.: (1 - 10*x^2 - 60*x^3 + 45*x^4 + 108*x^5 - 35*x^6 - 54*x^7 + 7*x^8 + 8*x^9) / ((1 + x)*(1 - 3*x + x^3)*(1 - 7*x - x^2 + 6*x^3 - x^5)) (conjectured). - _Colin Barker_, Jun 02 2017
%o (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>4)+($[(i+1)mod N]`-$[i]`>4))
%Y Cf. A025014.
%K nonn,base
%O 0,2
%A _R. H. Hardin_, Dec 28 2006
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