You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
morpholin-4-yl-[4-(3-thiophen-2-yl-[1,2,4]triazolo[4,3-b]pyridazin-6-yl)phenyl]methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H17N5O2S
assistant