You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule 2-chloro-1-(2,8-dimethyl-3,4,4a,9b-tetrahydro-1H-pyrido[4,3-b]indol-5-yl)ethanone ?
user
C15H19ClN2O
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