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 A046272 #9 Mar 08 2023 15:59:21
%S A046272 0,0,3,2,29,7,5,7993,67961,769,604661,2797,78233,1306069,783641,
%T A046272 7018498457,2821109,692665944473,66841,609359,4400629,21936950640377,
%U A046272 16217038422671,3022305360281,73838133832161689,992970137,170581728179
%N A046272 Largest prime substring in 6^n (0 if none).
%H A046272 Harvey P. Dale, <a href="/A046272/b046272.txt">Table of n, a(n) for n = 0..100</a>
%t A046272 Join[{0,0},Table[SelectFirst[Reverse[Union[FromDigits/@Flatten[Table[ Partition[ IntegerDigits[ 6^k],n,1],{n,IntegerLength[6^k]-1}],1]]],PrimeQ],{k,2,28}]] (* _Harvey P. Dale_, Mar 08 2023 *)
%Y A046272 Cf. A046264.
%K A046272 nonn
%O A046272 0,3
%A A046272 _Patrick De Geest_, Jun 15 1998