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A059743
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Number of points of norm^2 <= n^2 in the square lattice that are visible from the origin.
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0
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1, 5, 9, 17, 33, 49, 73, 89, 121, 153, 193, 225, 265, 313, 385, 441, 481, 545, 617, 673, 769, 833, 929, 1001, 1113, 1193, 1281, 1385, 1489, 1585, 1705, 1817, 1961, 2073, 2225, 2345, 2481, 2601, 2753, 2913, 3065, 3185, 3361, 3481, 3697, 3857, 4017, 4177
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| A lattice point (i,j) is "visible" from the origin if no other lattice point lies on the line segment from (0,0) to (i,j), which is equivalent to saying that i and j are relatively prime. By convention, we say that (0,0) is visible from the origin.
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REFERENCES
| Tom M. Apostol, "Introduction to Analytic Number Theory", Springer-Verlag, Section 3.8.
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CROSSREFS
| See also A000328, where visibility is not required.
Sequence in context: A081295 A180565 A160426 * A000322 A205539 A020737
Adjacent sequences: A059740 A059741 A059742 * A059744 A059745 A059746
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KEYWORD
| nonn
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AUTHOR
| John W. Layman (layman(AT)math.vt.edu), Oct 13 2001
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