You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[4-[[3-(4-ethoxyphenyl)-1,2,4-oxadiazol-5-yl]methyl]piperazin-1-yl]-2-methylpropan-1-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H26N4O3
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