You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N,N-dimethyl-3-(7-methyl-2-tricyclo[9.4.0.03,8]pentadeca-1(15),3,5,7,9,11,13-heptaenylidene)propan-1-amine is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H23N
assistant