I can only think of 14 of them, but i know there are a few more
1-chlorohexane 2-chlorohexane 3-chlorohexane
1-chloro-2-methylpentane 1-chloro-3-methylpentane
1-chloro-4-methylpentane 2-chloro-3-methylpentane
2-chloro-4-methylpentane 3-chloro-2-methylpentane
1-chloro-2,2-dimethylbutane 3-chloro-2,2-dimethylbutane
1-chloro-3,3-dimethylbutane 1-chloro-2,3-dimethylbutane
2-chloro-2,3-dimethylbutane