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 A039135 #19 Sep 08 2022 08:44:53
%S A039135 0,1,2,5,6,7,8,9,10,11,12,15,16,17,18,19,20,21,22,25,26,27,28,29,34,
%T A039135 43,50,51,52,55,56,57,58,59,60,61,62,65,66,67,68,69,70,71,72,75,76,77,
%U A039135 78,79,80,81,82,85,86,87,88,89,90,91,92,95,96,97,98,99,100,101,102
%N A039135 Numbers whose base-10 representation has the same number of 3's and 4's.
%H A039135 Daniel Starodubtsev, <a href="/A039135/b039135.txt">Table of n, a(n) for n = 1..10000</a>
%t A039135 Select[Range[0, 200], DigitCount[#, 10, 3] == DigitCount[#, 10, 4] &] (* _Vincenzo Librandi_, Oct 27 2016 *)
%o A039135 (Magma) [n: n in [0..120] | Multiplicity(S, 3) eq Multiplicity(S, 4) where S is {*d: d in Intseq(n)*}]; // _Vincenzo Librandi_, Oct 27 2016
%K A039135 nonn,base,easy
%O A039135 1,3
%A A039135 _Olivier Gérard_