You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-(1-methyl-2-phenylindol-3-yl)-2-octan-2-yl-4,5,6,7-tetrahydro-3H-isoindol-1-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C31H38N2O
assistant