Morgan's theorem is a generalization of Marion's theorem found by Ryan Morgan, a sophomore at Patapsco High School in Baltimore (Morgan 1994).
If the sides of a triangle are partitioned into equal segments for an odd integer and each
division point is connected to the opposite vertex, a central hexagon
is formed. Morgan's theorem states that the area of this
hexagon relative to the original triangle
is
(Morgan 1994, Watanabe et al. 1996). For , 5, 7, ..., this gives one over the centered nonagonal numbers
10, 28, 55, 91, 136, 190, 253, 325, 406, ... (OEIS A060544).