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 A018810 Number of lines through exactly 3 points of an n X n grid of points. 3
 0, 0, 0, 8, 4, 16, 36, 64, 100, 204, 252, 396, 572, 780, 1020, 1484, 1756, 2260, 2828, 3540, 4332, 5556, 6372, 7716, 9188, 10684, 12292, 14684, 16588, 19324, 22268, 25420, 28780, 33164, 36452, 41036, 45892, 51324, 57060, 64540, 70500, 77724, 85300, 93228 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 REFERENCES Lucien Pianaro, Jouer Jeux Mathematiques, 9(juillet 1993). [From Philippe Deléham, Apr 10 2009] LINKS Seiichi Manyama, Table of n, a(n) for n = 0..1000 S. Mustonen, On lines and their intersection points in a rectangular grid of points [From Seppo Mustonen, Apr 18 2009] FORMULA a(n) = 1/2 (f(n, 4) - 2 f(n, 3) + f(n, 2)) where f(n, k) = Sum ((n - |kx|)(n - |ky|)); -n

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Last modified May 26 16:42 EDT 2020. Contains 334626 sequences. (Running on oeis4.)