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 A088952 #15 Feb 16 2025 08:32:51
%S A088952 0,1,2,3,5,6,7,10,11,15,16,19,20,21,23,32,33,34,46,47,48,57,59,61,64,
%T A088952 65,69,96,97,100,102,104,138,140,142,145,146,173,177,178,183,185,194,
%U A088952 195,196,208,209,289,290,291,300,302,307,312,416,421,426,428,437,438
%N A088952 Numbers that are squarefree words in ternary representation.
%C A088952 A088950(a(n)) = 0.
%H A088952 Rémy Sigrist, <a href="/A088952/b088952.txt">Table of n, a(n) for n = 1..10000</a>
%H A088952 Rémy Sigrist, <a href="/A088952/a088952.gp.txt">PARI program for A088952</a>
%H A088952 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SquarefreeWord.html">Squarefree Word</a>
%t A088952 Select[Range[0, 500], MatchQ[IntegerDigits[#, 3], Except[{___, x__, x__, ___}]] &] (* _Vladimir Reshetnikov_, May 17 2016 *)
%o A088952 (PARI) See Links section.
%Y A088952 Cf. A007089, A088953.
%K A088952 nonn,base
%O A088952 1,3
%A A088952 _Reinhard Zumkeller_, Oct 25 2003