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 A355553 #25 Mar 22 2025 23:34:36 %S A355553 0,0,8,54,228,708,1980,4890,11528,26004,57384,123786,265596,563664, %T A355553 1192220,2511474,5279208,11064216,23156448,48361110,100859180, %U A355553 209996772,436635396,906562842,1879950384,3893566872,8054935784,16645591974,34363631412,70872295524,146036933100 %N A355553 Number of ways to select 3 or more collinear points from an n X n grid. %H A355553 Lucas A. Brown, <a href="/A355553/b355553.txt">Table of n, a(n) for n = 1..71</a> %H A355553 Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/A355553.py">A355553.py</a>. %e A355553 a(4)=54: There are 4 horizontal lines of length 4 and within a line of 4 dots are 5 ways to select a line 3 or longer. There are 2 diagonal lines of length 4 and 4 vertical lines of length 4. Finally there are 4 diagonals of length 3 these are: ((1,2),(2,3),(3,4)), ((2,1),(3,2),(4,3)), ((1,3),(2,2),(3,1)), ((2,4),(3,3),(4,2)). In total we have 5*10+4=54. %e A355553 4 . . . . %e A355553 3 . . . . %e A355553 2 . . . . %e A355553 1 . . . . %e A355553 1 2 3 4 %Y A355553 Cf. A000982 (1 X n), 2*A000982 (2 X n), A355551 (3 X n), A355552 (4 X n). %K A355553 nonn %O A355553 1,3 %A A355553 _Thomas Garrison_, Jul 14 2022 %E A355553 Corrected and extended by _Lucas A. Brown_, Nov 06 2022