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 A033002 #10 Feb 05 2014 03:15:01
%S A033002 5,10,15,80,90,95,160,165,175,240,245,250,1285,1290,1295,1440,1445,
%T A033002 1455,1520,1525,1530,2565,2570,2575,2640,2650,2655,2800,2805,2810,
%U A033002 3845,3850,3855,3920,3930,3935,4000,4005,4015,20560
%N A033002 Every run of digits of n in base 4 has length 2.
%C A033002 See A043291 and A033001 through A033014 for the analog in other bases, A033015 - A033029 for the variants with run lengths >= 2. - _M. F. Hasler_, Feb 04 2014
%H A033002 Vincenzo Librandi, <a href="/A033002/b033002.txt">Table of n, a(n) for n = 1..600</a>
%F A033002 a(n) = 5*A043308(n) (= 5*n for n<4). - _M. F. Hasler_, Feb 04 2014
%t A033002 Select[Range[10000], Union[Length/@Split[IntegerDigits[#, 4]]]=={2}&] (* _Vincenzo Librandi_, Feb 05 2014 *)
%K A033002 nonn,base
%O A033002 1,1
%A A033002 _Clark Kimberling_