You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[2-[4-(6-cyclopropyl-[1,2,4]triazolo[4,3-b]pyridazin-3-yl)piperidin-1-yl]ethyl]-1,4-oxazepan-3-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H28N6O2
assistant