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 A004602 #45 Aug 17 2022 16:20:47
%S A004602 1,0,0,1,0,2,1,1,0,1,2,2,2,2,0,1,0,2,1,1,0,0,2,1,1,1,1,1,0,2,2,1,2,2,
%T A004602 2,2,2,0,1,1,1,2,0,1,2,1,2,1,2,1,2,0,0,1,2,1,1,0,0,1,0,0,1,0,1,2,2,2,
%U A004602 0,2,2,2,1,2,0,1,2,0,1,2,1,1,1,2,1,0,1,2,1,0,1,1,2,0,0,2,2,0,1
%N A004602 Expansion of Pi in base 3.
%H A004602 G. C. Greubel, <a href="/A004602/b004602.txt">Table of n, a(n) for n = 2..10000</a>
%H A004602 Steve Pagliarulo, <a href="http://members.shaw.ca/francislyster/pi/pistats/pibase3.pdf">Stu's pi page: base 3</a> (23 pages).
%F A004602 a(n) = floor(Pi*3^(n-3)) - 3*floor(Pi*3^(n-4)), n>1. - _G. C. Greubel_, Mar 09 2018
%e A004602 10.0102110122220102110021111102212222201...
%t A004602 RealDigits[ N[ Pi, 105], 3] [[1]]
%t A004602 RealDigits[Pi,3,120][[1]] (* _Harvey P. Dale_, Jul 02 2021 *)
%t A004602 Table[ResourceFunction["NthDigit"][Pi, n, 3], {n, 1, 100}] (* _Joan Ludevid_, Jun 24 2022;easy to compute a(10000000)=1 with this function;requires Mathematica 12.0+ *)
%Y A004602 Pi in base b: A004601 (b=2), this sequence (b=3), A004603 (b=4), A004604 (b=5), A004605 (b=6), A004606 (b=7), A006941 (b=8), A004608 (b=9), A000796 (b=10), A068436 (b=11), A068437 (b=12), A068438 (b=13), A068439 (b=14), A068440 (b=15), A062964 (b=16), A060707 (b=60), A331313 (Pi in balanced ternary).
%Y A004602 Cf. A007514.
%K A004602 nonn,base,cons,easy
%O A004602 2,6
%A A004602 _N. J. A. Sloane_