Michael Filaseta, Allen Stenger, David Callan, Zachary Franco. When a Multiple of π/2 is Close to an Integer: 10640. The American Mathematical Monthly, 107(2):177-179, 2000. [doi]
@article{FilasetaSCF00,
title = {When a Multiple of π/2 is Close to an Integer: 10640},
author = {Michael Filaseta and Allen Stenger and David Callan and Zachary Franco},
year = {2000},
url = {http://www.jstor.org/stable/2589451},
researchr = {https://researchr.org/publication/FilasetaSCF00},
cites = {0},
citedby = {0},
journal = {The American Mathematical Monthly},
volume = {107},
number = {2},
pages = {177-179},
}