This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A126396 #9 Jun 01 2017 12:05:54
%S A126396 1,9,39,175,793,3611,16475,75229,343633,1569883,7172423,32769925,
%T A126396 149723361,684077955,3125520983,14280373781,65246447425,298108406323,
%U A126396 1362045450407,6223131628517,28433241805745,129910355608771
%N A126396 Number of base 9 n-digit numbers with adjacent digits differing by two or less.
%C A126396 [Empirical] a(base,n)=a(base-1,n)+5^(n-1) for base>=2n-1; a(base,n)=a(base-1,n)+5^(n-1)-2 when base=2n-2.
%F A126396 Conjectures from _Colin Barker_, Jun 01 2017: (Start)
%F A126396 G.f.: (1 + 3*x - 10*x^2 - 6*x^3 + 6*x^4 + 2*x^5) / (1 - 6*x + 5*x^2 + 8*x^3 - 4*x^4 - 2*x^5).
%F A126396 a(n) = 6*a(n-1) - 5*a(n-2) - 8*a(n-3) + 4*a(n-4) + 2*a(n-5) for n>5.
%F A126396 (End)
%o A126396 (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>2)+($[i+1]`-$[i]`>2))
%Y A126396 Cf. Base 9 differing by one or less A126363.
%K A126396 nonn,base
%O A126396 0,2
%A A126396 _R. H. Hardin_, Dec 28 2006