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 A046262 #9 Oct 10 2019 00:37:05
%S A046262 1,4,6,6,6,4,9,8,55,262,8,9,777,88,545,737,949,717,767,77,777,111,444,
%T A046262 77,767,42624,737,9,575,7117,606,6116,737,838,52825,717,828,58085,
%U A046262 914323419,676,747,585,3113,737,9,4224,959,838,33,5005,22822,12821,282
%N A046262 Largest palindromic substring in 4^n.
%t A046262 Table[Max[Select[FromDigits/@Flatten[Table[Partition[IntegerDigits[4^n],k,1],{k,IntegerLength[4^n]}],1],PalindromeQ]],{n,0,60}] (* _Harvey P. Dale_, Sep 25 2019 *)
%Y A046262 Cf. A046270.
%K A046262 nonn,base
%O A046262 0,2
%A A046262 _Patrick De Geest_, Jun 15 1998