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%I #10 Jun 03 2017 15:31:55
%S 1,7,37,175,925,4977,27067,147777,808165,4422703,24210127,132542813,
%T 725664307,3973047319,21752799623,119098967235,652080798837,
%U 3570220727531,19547391880633,107024353337437,585971402810715
%N Number of base 7 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 G.f.: (1 - 6*x^2 - 28*x^3 + 15*x^4 + 28*x^5 - 5*x^6 - 6*x^7) / ((1 - 2*x - x^2 + x^3)*(1 - 5*x - 3*x^2 + 2*x^3 + x^4)) (conjectured). - _Colin Barker_, Jun 03 2017
%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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