A126523 - OEIS

%I #7 Mar 31 2012 12:35:06

%S 1,28,232,1968,16832,144660,1247088,10773792,93218308,807453712,

%T 6999891340,60719731236,526944732908,4574529170580,39722471511860,

%U 344990169778032,2996656884892004,26032251950698948,226161890813945336

%N Number of base 28 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 28 differing by three or less A126496, two or less A126415, one or less A126382.

%K nonn,base

%O 0,2

%A _R. H. Hardin_, Dec 28 2006