Robin Chapman, Kimmo Eriksson, Richard P. Stanley. Problem 10847. The American Mathematical Monthly, 108(1):77, 2001. [doi]
@article{ChapmanES01,
title = {Problem 10847},
author = {Robin Chapman and Kimmo Eriksson and Richard P. Stanley},
year = {2001},
url = {http://www.jstor.org/stable/2695686},
researchr = {https://researchr.org/publication/ChapmanES01},
cites = {0},
citedby = {0},
journal = {The American Mathematical Monthly},
volume = {108},
number = {1},
pages = {77},
}