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Trajan AE Sestertius. 

Obv: IMP CAES NER TRAIANO  OPTIMO AVG GER DAC PARTHICO P M TR P COS VI P P, 
 laureate bust right 
Rev: REX PARTHIS DATVS, Trajan seated on raised  platform, praetorian at side, 
 presenting Parthamaspates to kneeling Parthia, SC in ex.

RIC 668.