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 A126418 #5 Mar 31 2012 12:35:06
%S A126418 1,31,149,725,3543,17361,85223,418899,2061105,10149405,50011235,
%T A126418 246566635,1216199805,6001382075,29624479933,146279954561,
%U A126418 722500541847,3569422111283,17638150070523,87175432519409,430936179702041
%N A126418 Number of base 31 n-digit numbers with adjacent digits differing by two or less.
%C A126418 [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
%o A126418 (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 A126418 Cf. Base 31 differing by one or less A126385.
%K A126418 nonn,base
%O A126418 0,2
%A A126418 _R. H. Hardin_, Dec 28 2006