You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl 4-(2,3,3a,4,5,6,7,7a-octahydroindol-1-yl)-2-methyl-2-(methylamino)pentanoate is the IUPAC name of a molecule. Please give its molecular formula.
user
C16H30N2O2
assistant