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 A244955 #16 Feb 01 2024 16:05:11
%S A244955 1,4,21,4,5,84,21,16,81,20,341,84,65,84,1365,16,17,324,1045,20,21,
%T A244955 1364,69,336,325,260,81,84,261,5460,341,64,1089,68,1365,324,4181,4180,
%U A244955 273,80,1025,84,5461,1364,5445,276,20821,336,1029,1300,4437,260,5141
%N A244955 Smallest positive multiple of n whose base-4 representation contains only 0's and 1's.
%H A244955 Harvey P. Dale, <a href="/A244955/b244955.txt">Table of n, a(n) for n = 1..1000</a>
%H A244955 Ed Pegg Jr., <a href="http://www.mathpuzzle.com/Binary.html">'Binary' Puzzle</a>
%H A244955 Eric M. Schmidt, <a href="/A004290/a004290_1.sage.txt">Sage code to compute this sequence</a> (use b=4)
%H A244955 Chai Wah Wu, <a href="http://www.jstor.org/stable/10.4169/amer.math.monthly.121.06.529">Pigeonholes and repunits</a>, Amer. Math. Monthly, 121 (2014), 529-533.
%t A244955 Module[{nn=10,b4},b4=Rest[FromDigits[#,4]&/@Tuples[{0,1},nn]];Table[SelectFirst[b4,Mod[ #,n]==0&],{n,60}]] (* _Harvey P. Dale_, Feb 01 2024 *)
%Y A244955 Cf. A004284 (written in base 4), A004290, A244954-A244960.
%K A244955 nonn,base
%O A244955 1,2
%A A244955 _Eric M. Schmidt_, Jul 09 2014
%E A244955 Data corrected, offset corrected, and b-file replaced by _Harvey P. Dale_, Feb 01 2024