You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-[4-(2-hydroxy-2-methylpropyl)piperazin-1-yl]-1-(4-methylpiperazin-1-yl)ethanone by IUPAC nomenclature, provide its molecular formula.
user
C15H30N4O2
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