Richard P. Stanley. Problem 11348. The American Mathematical Monthly, 115(3):262, 2008. [doi]
@article{Stanley08-0, title = {Problem 11348}, author = {Richard P. Stanley}, year = {2008}, url = {http://www.jstor.org/stable/27642452}, researchr = {https://researchr.org/publication/Stanley08-0}, cites = {0}, citedby = {0}, journal = {The American Mathematical Monthly}, volume = {115}, number = {3}, pages = {262}, }