I give explicit values for the constant implied by an Omega-estimate due to Chen and Chen [CC] on the average of the sum of the divisors of n which are relatively coprime to any given integer a.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-cm108-2-1, author = {Y.-F. S. P\'etermann}, title = {On fluctuations in the mean of a sum-of-divisors function, II}, journal = {Colloquium Mathematicae}, volume = {107}, year = {2007}, pages = {171-177}, zbl = {1187.11034}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm108-2-1} }
Y.-F. S. Pétermann. On fluctuations in the mean of a sum-of-divisors function, II. Colloquium Mathematicae, Tome 107 (2007) pp. 171-177. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm108-2-1/