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 A279453 #9 Dec 17 2016 10:58:24 %S A279453 1,1,1,1,2,1,1,1,3,8,14,17,9,2,1,3,21,73,202,306,285,115,20,1,6,49, %T A279453 301,1397,4361,9110,11810,8679,2929,288,1,6,93,890,6582,34059,126396, %U A279453 326190,568134,624875,390426,111798,8791,1,10,171,2321,24185,185181,1055025 %N A279453 Triangle read by rows: T(n, k) is the number of nonequivalent ways to place k points on an n X n square grid so that no more than 2 points are on a vertical or horizontal straight line. %C A279453 Length of n-th row is A272651(n) + 1, where A272651(n) is the maximal number of points that can be placed under the condition mentioned. %C A279453 Rotations and reflections of placements are not counted. If they are to be counted, see A279445. %C A279453 For condition "no more than 2 points on a straight line at any angle", see A235453. %H A279453 Heinrich Ludwig, <a href="/A279453/b279453.txt">Table of n, a(n) for n = 1..109</a> %e A279453 The table begins with T(1, 0): %e A279453 1 1 %e A279453 1 1 2 1 1 %e A279453 1 3 8 14 17 9 2 %e A279453 1 3 21 73 202 306 285 115 20 %e A279453 1 6 49 301 1397 4361 9110 11810 8679 2929 288 %e A279453 ... %e A279453 T(4, 3) = 73 because there are 73 nonequivalent ways to place 3 points on a 4 X 4 square grid so that no more than 2 points are on a vertical or horizontal straight line. %Y A279453 Row sums give A279454. %Y A279453 Columns 2..8: A008805, A014409, A279454, A279455, A279456, A279457, A279458. %Y A279453 Diagonal T(n, n) is A279452. %Y A279453 Cf. A279445, A235453. %K A279453 nonn,tabf %O A279453 1,5 %A A279453 _Heinrich Ludwig_, Dec 17 2016