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%I #7 Mar 31 2012 12:35:06
%S 1,25,205,1725,14645,124977,1069941,9179469,78869491,678323799,
%T 5838030793,50269401543,432996699399,3730477803939,32144938184273,
%U 277017865876053,2387456054541987,20577155216208681,177357954676723141
%N Number of base 25 n-digit numbers with adjacent digits differing by four or less.
%C [Empirical] a(base,n)=a(base-1,n)+9^(n-1) for base>=4n-3; a(base,n)=a(base-1,n)+9^(n-1)-2 when base=4n-4
%o (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>4)+($[i+1]`-$[i]`>4))
%Y Cf. Base 25 differing by three or less A126493, two or less A126412, one or less A126379.
%K nonn,base
%O 0,2
%A _R. H. Hardin_, Dec 28 2006
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