At 04:44 PM 10/21/2004, Leroy Quet wrote: Another sequence: >How many ways are there to arrange the maximum number of dots in an >n-by-n grid so that no dots are colinear? The sequence A000769 has 15 terms for the number of ways of placing 2n points with the condition, and states that there are no "2n" solutions for sufficiently large n (surprise to me).