You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-formamido-N-[2-[4-(2-tricyclo[9.4.0.03,8]pentadeca-1(15),3,5,7,9,11,13-heptaenylidene)piperidin-1-yl]ethyl]butanamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C27H31N3O2
assistant