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Integer points on circles. (Posted on 2011-02-28) Difficulty: 3 of 5
If a circle is centered on the origin and has radius r, it may pass through some points with integer coordinates. In fact, by symmetry, this will be a multiple of 4.

Find the smallest radius that will pass through 4n integer points where n=1,2,3,4,5.

Feel free to go further.

See The Solution Submitted by Jer    
Rating: 3.5000 (2 votes)

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Hints/Tips OEIS sequence | Comment 13 of 14 |

A071383 - Squared radii of the circles around (0,0) that contain record numbers of lattice points.

 0, 1, 5, 25, 65, 325, 1105, 4225, 5525, 27625, 71825, 138125, 160225, 801125, 2082925, 4005625, 5928325, 29641625, 77068225, 148208125, 243061325, 1215306625, 3159797225, 6076533125, 12882250225, 53716552825, 64411251125


  Posted by Brian Smith on 2011-03-01 11:26:35
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