%I #8 Mar 31 2012 12:35:02
%S 1,16,146,1126,10006,90766,841412,7895904,74715854,710834734,
%T 6786655906,64943303298,622375932004,5970118647444,57303035279202,
%U 550227097897606,5284636214132958,50764242418318486,487691693453055908
%N Number of base 16 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