On the Number of Subsets Relatively Prime to an Integer
Laboratoire de Mathématiques Pures et Appliquées
Université du Littoral
Department of Mathematics
St. Catharines, Ontario L2S 3A1
Fix a positive integer and a finite set whose elements are in
arithmetic progression. We give a formula for the number of nonempty
subsets of this set that are coprime to the given integer. A similar
formula is given when we restrict our attention to the subsets having
the same fixed cardinality. These formulas generalize previous results
of El Bachraoui.
Full version: pdf,
Received October 22 2008;
revised version received December 13 2008.
Published in Journal of Integer Sequences, December 13 2008.
Journal of Integer Sequences home page