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 A059870 #8 Aug 11 2024 14:41:33 %S A059870 2,3,5,6,7,8,10,11,15,17,18,20,22,23,26,31,34 %N A059870 Numbers n such that there exist no palindromic octagonal numbers of length n. %H A059870 P. De Geest, <a href="https://www.worldofnumbers.com/octa.htm">Palindromic octagonals</a> %Y A059870 Cf. A034822, A034307, A059868, A059869, A000567, A057106, A057107. %K A059870 nonn,base,hard %O A059870 1,1 %A A059870 _Patrick De Geest_, Feb 15 2000 %E A059870 a(13)-a(17) from World!Of Numbers link entered by _Michel Marcus_, Mar 04 2014