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%I #7 Mar 31 2012 12:35:06
%S 1,22,178,1482,12458,105294,892794,7585162,64523192,549288946,
%T 4678354648,39857857006,339636526202,2894437457458,24668599937974,
%U 210253750878176,1792068953052004,15274708515161126,130195398889209326
%N Number of base 22 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 22 differing by three or less A126490, two or less A126409, one or less A126376.
%K nonn,base
%O 0,2
%A _R. H. Hardin_, Dec 28 2006
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