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 A279452 #7 Dec 23 2016 18:55:28 %S A279452 1,2,14,202,4361,126396,4444935,182567862,8560638040,451107721000 %N A279452 Number of nonequivalent ways to place n points on an n X n square grid so that no more than 2 points are on a vertical or horizontal straight line. %C A279452 Rotations and reflections of placements are not counted. If they are to be counted, see A279444. %e A279452 There are a(3) = 14 nonequivalent ways to place 3 points on a 3 X 3 square grid under the condition mentioned above: %e A279452 XX XX. XX. XX. XX. XX. X.X X.X X X X.. X.. X.. .X. .X. %e A279452 ..X ... X.. .X. ... ... .X. ... ... .XX .X. ..X XX. X.X %e A279452 ... ..X ... ... X.. .X. ... X.. .X. ... ..X .X. ... ... %Y A279452 Cf. A279444, A279453. %K A279452 nonn,more %O A279452 1,2 %A A279452 _Heinrich Ludwig_, Dec 23 2016