%I #8 Mar 31 2012 12:35:02
%S 1,19,229,2371,28117,340639,4206175,52452531,657946661,8280460237,
%T 104408596879,1317891532471,16644977894179,210297040134369,
%U 2657451892030143,33584889901686421,424471412263606133
%N Number of base 19 circular n-digit numbers with adjacent digits differing by 7 or less.
%C [Empirical] a(base,n)=a(base-1,n)+F(7) for base>=7.int(n/2)+1 and F(d) is the largest coefficient in (1+x+...+x^(2d))^n
%o (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>7)+($[(i+1)mod N]`-$[i]`>7))
%K nonn,base
%O 0,2
%A _R. H. Hardin_, Dec 28 2006
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