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Search: id:A018810
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| A018810 |
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Number of lines through exactly 3 points of an n X n grid of points. |
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+0
1
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| 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; listen)
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OFFSET
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0,4
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REFERENCES
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Lucien Pianaro, Jouer Jeux Mathematiques, 9(juillet 1993). [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Apr 10 2009]
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LINKS
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S. Mustonen, On lines and their intersection points in a rectangular grid of points [From Seppo Mustonen (seppo.mustonen(AT)helsinki.fi), Apr 18 2009]
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FORMULA
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1/2 (f(n, 4) - 2 f(n, 3) + f(n, 2)) where f(n, k) = Sum ((n - |kx|)(n - |ky|)); -n<kx<n, -n<ky<n, (x, y)=1. [From Seppo Mustonen (seppo.mustonen(AT)helsinki.fi), Apr 18 2009]
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CROSSREFS
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Sequence in context: A156279 A131873 A040059 this_sequence A070485 A151726 A070290
Adjacent sequences: A018807 A018808 A018809 this_sequence A018811 A018812 A018813
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KEYWORD
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nonn
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AUTHOR
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David W. Wilson (davidwwilson(AT)comcast.net)
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