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 A001738 #22 Feb 02 2022 07:24:07
%S A001738 0,1,11,100,121,221,1100,1211,2101,10000,10201,11111,12100,20021,
%T A001738 21021,22100,100111,101201,110000,111101,112211,121100,122221,201121,
%U A001738 210100,212011,221001,1000000,1002001,1011011,1020100,1022121,1101221,1111100,1120211
%N A001738 a(n) = n^2 written in base 3.
%H A001738 T. D. Noe, <a href="/A001738/b001738.txt">Table of n, a(n) for n = 0..1000</a>
%F A001738 a(n) = A007089(A000290(n)). - _Jason Kimberley_, Dec 13 2012
%t A001738 Table[FromDigits[IntegerDigits[n^2, 3]], {n, 0, 50}] (* _T. D. Noe_, Aug 10 2012 *)
%Y A001738 Cf. A007089, A000290.
%K A001738 base,easy,nonn
%O A001738 0,3
%A A001738 _N. J. A. Sloane_