You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 4-[6-[7-[9-(4-isocyanophenyl)-4b,8a-dimethyl-5,6,7,8-tetrahydrocarbazol-3-yl]-9,9-diphenylfluoren-2-yl]-4a,9a-dimethyl-1,2,3,4-tetrahydrocarbazol-9-yl]benzonitrile by IUPAC nomenclature, provide its molecular formula.
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C67H58N4
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