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 A020334 #22 Apr 06 2021 10:00:51
%S A020334 7,14,21,28,35,222,259,296,333,370,407,444,481,518,555,592,629,666,
%T A020334 703,740,777,814,851,888,925,962,999,1036,1073,1110,1147,1184,1221,
%U A020334 1258,1295,7812,8029,8246,8463,8680,8897,9114,9331,9548,9765,9982,10199,10416
%N A020334 Numbers whose base-6 representation is the juxtaposition of two identical strings.
%H A020334 Amiram Eldar, <a href="/A020334/b020334.txt">Table of n, a(n) for n = 1..10000</a>
%F A020334 a(n) = n*6^floor(log_6(n)+1) + n. - _Ilya Gutkovskiy_, Jan 26 2018
%e A020334 296_10 = 1212_6. - _Jon E. Schoenfield_, Feb 11 2021
%t A020334 jtiQ[n_]:=Module[{idn6=IntegerDigits[n,6],len},len=Length[idn6];EvenQ[ len] && Take[idn6,len/2]==Take[idn6,(-len/2)]]; Select[ Range[ 11000], jtiQ] (* _Harvey P. Dale_, May 29 2016 *)
%t A020334 a[n_] := n + n*6^Floor[Log[6, n] + 1]; Array[a, 50] (* _Amiram Eldar_, Apr 06 2021 *)
%Y A020334 Cf. A020330, A020331, A020332, A020333, A020335, A020336, A020337, A020338.
%K A020334 nonn,base
%O A020334 1,1
%A A020334 _David W. Wilson_, Melia Aldridge (ma38(AT)spruce.evansville.edu)