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 A362016 #18 Aug 24 2023 09:43:37 %S A362016 0,1,4,8,13,20,28,38,50,61,75,90,108,124,139 %N A362016 Maximal number of unmarked cells with at least 3 marked neighboring cells in the n X n kings' graph. %C A362016 The value of r = lim sup a(n) / n^2 is in the half-open interval [2/3, 8/11). %C A362016 It appears from the computed terms that r = 2/3. %H A362016 Tomas Rigaux, <a href="/A362016/a362016.py.txt">Python program</a> %e A362016 a(2) = 1, as the only pattern is %e A362016 .X %e A362016 XX %e A362016 a(9) = 50, with a similar pattern to prove that r >= 2/3: %e A362016 X.......X %e A362016 .XXXXXXX. %e A362016 X.......X %e A362016 ......... %e A362016 XXXXXXXXX %e A362016 ......... %e A362016 X.......X %e A362016 .XXXXXXX. %e A362016 X.......X %e A362016 a(10) = 61, and a pattern that reaches that is %e A362016 X..X...X.. %e A362016 XX.X.X.X.X %e A362016 .......... %e A362016 .X.XX.X.XX %e A362016 XX....X... %e A362016 ....X....X %e A362016 X.XX..XX.X %e A362016 X....X.... %e A362016 ...X....XX %e A362016 XX.X.XX.X. %Y A362016 If we only want 1 marked neighbor, we get n^2 - A075561(n). %K A362016 nonn,hard,more %O A362016 1,3 %A A362016 _Tomas Rigaux_, Apr 04 2023