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 A235456 #10 Nov 16 2016 15:52:02 %S A235456 5,217,3192,27041,149217,650566,2317137,7124316,19459757,48617666, %T A235456 111797647,241575473 %N A235456 Number of non-equivalent (mod D_4) ways to arrange 5 points on an n X n square grid so that no three points are collinear. %C A235456 Column 5 of A235453. %C A235456 Without the restriction "non-equivalent (mod D_4)" the numbers are given by A194190, n >= 3. %e A235456 There are a(3) = 5 non-equivalent ways to place 5 points (X) on a 3 X 3 grid: %e A235456 X . X X . X . X X X X . X . X %e A235456 X . X X . . X . X X . . X X . %e A235456 . X . . X X . X . . X X . X . %Y A235456 Cf. A235453, A194190, A235454 (3 points), A235455 (4 points), A235457 (6 points), A235458 (7 points) %K A235456 nonn,more %O A235456 3,1 %A A235456 _Heinrich Ludwig_, Jan 12 2014 %E A235456 a(13), a(14) from _Heinrich Ludwig_, Nov 16 2016