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 A235454 #15 Nov 16 2016 15:52:45 %S A235454 1,13,70,290,867,2266,5068,10475,19764,35406,59817,97375,152154 %N A235454 Number of non-equivalent (mod D_4) ways to arrange 3 points on an n X n square grid so that they are not collinear. %C A235454 Column 3 of A235453. %C A235454 Also number of non-equivalent triangles in an n X n grid. %C A235454 Without the restriction "non-equivalent (mod D_4)" the numbers are given by A045996, n >= 2. %e A235454 There are a(3) = 13 non-equivalent ways to place 3 points on a 3 X 3 grid: %e A235454 . . . . . . X . . . X . . . . . X . . X . %e A235454 X . . X . . . . . . . . . X . X . X X X . %e A235454 X X . X . X X . X X . X X . X . . . . . . %e A235454 - %e A235454 . . . . . . . . . . X . . X . . . X %e A235454 X . X . X X X X . . . X X . . X . . %e A235454 X . . X . . X . . X . . X . . X . . %Y A235454 Cf. A235453, A045996, A235455 (4 points), A235456 (5 points), A235457 (6 points), A235458 (7 points). %K A235454 nonn,more %O A235454 2,2 %A A235454 _Heinrich Ludwig_, Jan 12 2014 %E A235454 a(13), a(14) from _Heinrich Ludwig_, Nov 16 2016