%I #8 Mar 31 2012 12:35:02
%S 1,19,179,1399,12679,117169,1108151,10622169,102843047,1002906517,
%T 9832026699,96763261669,955021583503,9445371945561,93558608546267,
%U 927743558287129,9207050413918087,91425186769710909,908226948062391227
%N Number of base 19 circular n-digit numbers with adjacent digits differing by 5 or less.
%C [Empirical] a(base,n)=a(base-1,n)+F(5) for base>=5.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]`-$[(i+1)mod N]`>5)+($[(i+1)mod N]`-$[i]`>5))
%K nonn,base
%O 0,2
%A _R. H. Hardin_, Dec 28 2006