You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[(6S)-6-(imidazo[1,2-b]pyridazin-6-ylmethyl)-1,4-oxazepan-4-yl]-(1H-imidazol-5-yl)methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C16H18N6O2
assistant