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 A004659 #14 Sep 08 2022 08:44:33
%S A004659 1,3,14,102,311,1433,10404,32222,202221,1112213,3342144,21132042,
%T A004659 114001231,402004243,2211023334,12133131112,42004443341,231024441123,
%U A004659 1243134423424,4340014331332,24120104100101
%N A004659 Powers of 3 written in base 5.
%H A004659 Vincenzo Librandi, <a href="/A004659/b004659.txt">Table of n, a(n) for n = 0..1000</a>
%t A004659 Table[FromDigits[IntegerDigits[3^n, 5]], {n, 0, 40}] (* _Vincenzo Librandi_, Jun 07 2013 *)
%o A004659 (PARI) for(n=0,30, print1(fromdigits(digits(3^n, 5)), ", ")) \\ _G. C. Greubel_, Sep 10 2018
%o A004659 (Magma) [Seqint(Intseq(3^n, 5)): n in [0..30]]; // _G. C. Greubel_, Sep 10 2018
%K A004659 nonn,base,easy
%O A004659 0,2
%A A004659 _N. J. A. Sloane_