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Number of base 21 circular n-digit numbers with adjacent digits differing by 6 or less.
0

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

%S 1,21,231,2121,22547,244601,2714271,30517333,346395491,3958011609,

%T 45437784111,523343937005,6041702589491,69860441606457,

%U 808706293207743,9368913912846221,108598284502838979,1259272889680954201

%N Number of base 21 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