MathDB

There are

n

boyfriend-girlfriend pairs at a party. Initially all the girls sit at a round table. For the first dance, each boy invites one of the girls to dance with.After each dance, a boy takes the girl he danced with to her seat, and for the next dance he invites the girl next to her in the counterclockwise direction. For which values of

n

can the girls be selected in such a way that in every dance at least one boy danced with his girlfriend, assuming that there are no less than

n

dances?

Problem Statement