You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[1-(oxolan-3-yl)ethyl]-1,3,4,6,7,8,9,9a-octahydropyrido[1,2-a]pyrazine is the IUPAC name of a molecule. Please give its molecular formula.
user
C14H26N2O
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