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 A033023 #20 Aug 13 2021 19:13:52
%S A033023 11,22,33,44,55,66,77,88,99,111,222,333,444,555,666,777,888,999,1100,
%T A033023 1111,1122,1133,1144,1155,1166,1177,1188,1199,2200,2211,2222,2233,
%U A033023 2244,2255,2266,2277,2288,2299,3300,3311,3322,3333
%N A033023 Numbers whose base-10 expansion has no run of digits with length < 2.
%C A033023 Contains A014181 as subsequence. A115853 is a supersequence. - _M. F. Hasler_, Jun 24 2016
%H A033023 Giovanni Resta, <a href="/A033023/b033023.txt">Table of n, a(n) for n = 1..10000</a> (first 1100 terms from Vincenzo Librandi)
%H A033023 Giovanni Resta, <a href="http://www.numbersaplenty.com/set/zygodrome/">Zygodrome</a>
%t A033023 Select[Range[10000], Min[Length/@Split[IntegerDigits[#, 10]]]>1&] (* _Vincenzo Librandi_, Feb 05 2014 *)
%o A033023 (PARI) is(n)={n=digits(n);while(#n>2 && n[2]==n[1], n=if(n[3]==n[1],n[^1],n[3..-1]));#n>1&&n[1]==n[2]} \\ _M. F. Hasler_, Jun 24 2016
%Y A033023 Cf. A014181, A115853.
%K A033023 nonn,base
%O A033023 1,1
%A A033023 _Clark Kimberling_