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 A344719 #22 Jun 13 2021 03:16:29 %S A344719 1,2,5,8,11,17,21,28,35,42,51,60,69,80,91 %N A344719 Minimum number of cells in an n X n grid that need to be painted so that each unpainted cell is orthogonally adjacent to exactly two painted cells. %H A344719 Dmitry Kamenetsky, <a href="/A344719/a344719.txt">Example solutions for n <= 11</a>. %H A344719 Puzzling StackExchange, <a href="https://puzzling.stackexchange.com/questions/110250/paint-eleven-squares">Paint Eleven Squares</a>, 2021. %Y A344719 Cf. A344301. %K A344719 nonn,hard,more %O A344719 1,2 %A A344719 _Dmitry Kamenetsky_, May 28 2021 %E A344719 a(12)-a(15) from _Bert Dobbelaere_, Jun 13 2021