A Lattice Point configuration with no three points Collinear and no four Concyclic. An example is the 6-cluster (0, 0), (132, ), (546, ), (960, ), (1155, 540), (546, 1120). Call the Radius of the smallest Circle centered at one of the points of an N-cluster which contains all the points in the N-cluster the Extent. Noll and Bell (1989) found 91 nonequivalent prime 6-clusters of Extent less than , but found no 7-clusters.

**References**

Guy, R. K. *Unsolved Problems in Number Theory, 2nd ed.* New York: Springer-Verlag, p. 187, 1994.

Noll, L. C. and Bell, D. I. ``-clusters for .'' *Math. Comput.* **53**, 439-444, 1989.

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1999-05-25