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 A046265 #7 Oct 10 2019 00:36:28 %S A046265 1,7,9,343,4,8,11,8,8,353,282,77,8,88,22,747,696,232,979,9889,2662, %T A046265 85458,909,747,414,686,77,363,99,797,878,57775,2992,707,959,818,717, %U A046265 757,717,198891,909,959,482284,18381,9,3003,494494,63036,888,5775 %N A046265 Largest palindromic substring in 7^n. %Y A046265 Cf. A046273. %K A046265 nonn,base %O A046265 0,2 %A A046265 _Patrick De Geest_, Jun 15 1998