You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (3'R,4'S)-N-cyclohexyl-2-oxo-4'-phenylspiro[1H-indole-3,1'-2,3,4,9-tetrahydropyrido[3,4-b]indole]-3'-carboxamide by IUPAC nomenclature, provide its molecular formula.
user
C31H30N4O2
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