Abstract: | Let d1 d2 dp denote the nonincreasing sequence d1, …, d1, d2, …, d2, …, dp, …, dp, where the term di appears ki times (i = 1, 2, …, p). In this work the author proves that the maximal 2-sequences: 7361515, 7561517, 7761519 are planar graphical, in contrast to a conjecture by Schmeichel and Hakimi. |