You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[8-(3-aminopropyl)-4,11-dimethyl-1,4,8,11-tetrazacyclotetradec-1-yl]propan-1-amine is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H42N6
assistant