%I #8 Mar 31 2012 12:35:02
%S 1,31,361,3391,37237,416111,4761901,55250583,648017421,7662743017,
%T 91199048321,1091067528549,13108510159921,158042063686499,
%U 1910968040115173,23162642662833881,281323809804798781
%N Number of base 31 circular n-digit numbers with adjacent digits differing by 6 or less.
%C [Empirical] a(base,n)=a(base-1,n)+F(6) for base>=6.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]`-$[(i+1)mod N]`>6)+($[(i+1)mod N]`-$[i]`>6))
%K nonn,base
%O 0,2
%A _R. H. Hardin_, Dec 28 2006
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