cp's OEIS Frontend

A126530 Number of base 9 n-digit numbers with adjacent digits differing by five or less.

%I A126530 #11 Jun 01 2017 12:06:46
%S A126530 1,9,69,541,4231,33101,258953,2025831,15848391,123984439,969949627,
%T A126530 7588067405,59362636295,464403174075,3633098554089,28422297349753,
%U A126530 222352070721709,1739494972761653,13608340819322255,106460175369651261
%N A126530 Number of base 9 n-digit numbers with adjacent digits differing by five or less.
%C A126530 [Empirical] a(base,n)=a(base-1,n)+11^(n-1) for base>=5n-4; a(base,n)=a(base-1,n)+11^(n-1)-2 when base=5n-5.
%F A126530 Conjectures from _Colin Barker_, Jun 01 2017: (Start)
%F A126530 G.f.: (1 + 2*x - x^2 - x^3) / ((1 + x)*(1 - 8*x + x^2 + 3*x^3)).
%F A126530 a(n) = 7*a(n-1) + 7*a(n-2) - 4*a(n-3) - 3*a(n-4) for n>3.
%F A126530 (End)
%o A126530 (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>5)+($[i+1]`-$[i]`>5))
%Y A126530 Cf. Base 9 differing by four or less A126504, three or less A126477, two or less A126396, one or less A126363.
%K A126530 nonn,base
%O A126530 0,2
%A A126530 _R. H. Hardin_, Dec 28 2006