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 A171901 #24 Jun 08 2020 05:31:19
%S A171901 11,22,33,44,55,66,77,88,99,100,110,111,112,113,114,115,116,117,118,
%T A171901 119,122,133,144,155,166,177,188,199,200,211,220,221,222,223,224,225,
%U A171901 226,227,228,229,233,244,255,266,277,288,299,300,311,322,330,331,332,333
%N A171901 Numbers with at least two identical neighboring digits in their decimal representation.
%C A171901 A171902(n) = a(n+1) - a(n) <= 11.
%C A171901 Complement of A043096; A196368(a(n)) = 0.
%H A171901 Reinhard Zumkeller, <a href="/A171901/b171901.txt">Table of n, a(n) for n = 1..10000</a>
%t A171901 Select[Range[350],SequenceCount[IntegerDigits[#],{___,x_,x_,___}]>0&] (* The program uses the SequenceCount function from Mathematica version 10 *) (* _Harvey P. Dale_, May 14 2016 *)
%o A171901 (Haskell)
%o A171901 import Data.List (elemIndices)
%o A171901 a171901 n = a171901_list !! n
%o A171901 a171901_list = elemIndices 0 a196368_list
%o A171901 -- _Reinhard Zumkeller_, Oct 29 2001
%o A171901 (Python)
%o A171901 def is_ok(n):
%o A171901 s = str(n)
%o A171901 return any(s[i] == s[i - 1] for i in range(1, len(s)))
%o A171901 A171901_list = [n for n in range(400) if is_ok(n)] # _Chai Wah Wu_, Feb 14 2019
%Y A171901 Cf. A044821, A171903, A171904.
%K A171901 base,nonn
%O A171901 1,1
%A A171901 _Reinhard Zumkeller_, Feb 07 2010