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 A033088 #23 Jul 28 2023 23:28:50 %S A033088 1,2,3,4,5,6,7,8,9,13,20,24,31,35,42,46,53,57,64,68,75,79,86,97,131, %T A033088 135,202,242,246,313,353,357,420,424,464,468,531,535,575,579,642,646, %U A033088 686,753,757,797,864,868,975,979,1313,1353,1357,2020 %N A033088 Numbers in which all pairs of consecutive digits differ by 2. %C A033088 If we restrict the maximum number of digits in the number to n, n >= 1, the sequence is finite and the last term is 9797...97 if n is even or 9797..9 if n is odd. - _Enrique Navarrete_, Dec 01 2017 %H A033088 Iain Fox, <a href="/A033088/b033088.txt">Table of n, a(n) for n = 1..947</a> %o A033088 (PARI) is(n) = for(i=2, #n=digits(n), if(abs(n[i]-n[i-1]) != 2, return(0))); 1 \\ _Iain Fox_, Dec 01 2017 %K A033088 nonn,base %O A033088 1,2 %A A033088 _Clark Kimberling_