You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (2R,3S)-N-[(2S)-3,3-dimethyl-1-oxo-1-(pyridin-2-ylamino)butan-2-yl]-3-methoxy-2-(2-methylpropyl)-N'-phosphanylbutanediamide by IUPAC nomenclature, provide its molecular formula.
user
C20H33N4O4P
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