cp's OEIS Frontend

A126503 Number of base 8 n-digit numbers with adjacent digits differing by four or less.

%I A126503 #11 Jun 01 2017 12:06:26
%S A126503 1,8,52,348,2322,15500,103462,690610,4609826,30770620,205394096,
%T A126503 1371006978,9151480836,61086196378,407750773322,2721739165358,
%U A126503 18167627307952,121269034961780,809471627267722,5403228578160660
%N A126503 Number of base 8 n-digit numbers with adjacent digits differing by four or less.
%C A126503 [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.
%F A126503 Conjectures from _Colin Barker_, Jun 01 2017: (Start)
%F A126503 G.f.: (1 + 2*x - x^2 - x^3) / (1 - 6*x - 5*x^2 + 3*x^3 + 2*x^4).
%F A126503 a(n) = 6*a(n-1) + 5*a(n-2) - 3*a(n-3) - 2*a(n-4) for n>3.
%F A126503 (End)
%o A126503 (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 A126503 Cf. Base 8 differing by three or less A126476, two or less A126395, one or less A126362.
%K A126503 nonn,base
%O A126503 0,2
%A A126503 _R. H. Hardin_, Dec 28 2006