You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-methyl-5-[4-(1,4,5,6-tetrahydrocyclopenta[c]pyrazole-3-carbonyl)piperazin-1-yl]pyridazin-3-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C16H20N6O2
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