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 A126531 #11 Jun 01 2017 12:06:52
%S A126531 1,10,80,660,5430,44692,367826,3027314,24915652,205062892,1687725824,
%T A126531 13890462738,114322452324,940906242802,7743925534706,63734705924048,
%U A126531 524554726284436,4317234336897124,35532064407664766,292438978880594940
%N A126531 Number of base 10 n-digit numbers with adjacent digits differing by five or less.
%C A126531 [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 A126531 Conjectures from _Colin Barker_, May 31 2017: (Start)
%F A126531 G.f.: (1 - x)*(1 + 3*x - x^3) / ((1 + x)*(1 - 9*x + 6*x^2 + 3*x^3 - 2*x^4)).
%F A126531 a(n) = 8*a(n-1) + 3*a(n-2) - 9*a(n-3) - a(n-4) + 2*a(n-5) for n>4.
%F A126531 (End)
%o A126531 (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 A126531 Cf. Base 10 differing by four or less A126505, three or less A126478, two or less A126397, one or less A126364.
%K A126531 nonn,base
%O A126531 0,2
%A A126531 _R. H. Hardin_, Dec 28 2006