%I #7 Mar 31 2012 12:35:01
%S 1,19,121,619,3697,22389,138973,874277,5559985,35648953,230069191,
%T 1492690207,9727027549,63617931357,417371683689,2745447557409,
%U 18100412004049,119567904627743,791186114040565,5243056748156375
%N Number of base 19 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
%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