You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 6-ethyl-2-methyl-N-[2-methyl-1-(3-pyridin-3-yl-1,2,4-oxadiazol-5-yl)propyl]pyrimidin-4-amine by IUPAC nomenclature, provide its molecular formula.
user
C18H22N6O
assistant