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%I #11 Jun 04 2017 06:46:57
%S 1,6,30,138,694,3526,18012,92140,471566,2413794,12356010,63250314,
%T 323779348,1657433992,8484446994,43432107538,222330112286,
%U 1138113767838,5826034724844,29823627148788,152667942902854
%N Number of base 6 circular n-digit numbers with adjacent digits differing by 3 or less.
%C [Empirical] a(base,n)=a(base-1,n)+A025012(n+1) for base>=3.int(n/2)+1.
%F Conjectures from _Colin Barker_, Jun 04 2017: (Start)
%F G.f.: (1 - 3*x^2 - 16*x^3 + 3*x^4 + 8*x^5) / ((1 - x - x^2)*(1 - 5*x - x^2 + 2*x^3)).
%F a(n) = 6*a(n-1) - 3*a(n-2) - 8*a(n-3) + a(n-4) + 2*a(n-5) for n>5.
%F (End)
%o (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>3)+($[(i+1)mod N]`-$[i]`>3))
%K nonn,base
%O 0,2
%A _R. H. Hardin_, Dec 28 2006
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