%I #8 Mar 31 2012 12:35:02

%S 1,26,334,3554,43902,553306,7135630,93271834,1231458766,16376454818,

%T 218938689224,2938429752768,39550154759946,533443662253450,

%U 7205953681467518,97448916863238514,1318905084028233358

%N Number of base 26 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