Inter raced to a two-goal lead in less than 10 minutes against their Serie B opponents when Mauro Icardi converted a penalty and Candreva fired home the rebound after an Icardi header struck the post.
Dalbert blasted the third just before halftime in the round of 16 tie, the Brazilian's first goal for Inter since his move from Nice 18 months ago.
Argentine forward Martinez added two more in the second half and Candreva completed the scoring while Roberto Insigne and Filippo Bandinelli replied for the visitors.
Inter were ordered to play two matches behind closed doors after a group of fans insulted Senegal defender Koulibaly with racist chants and animal noises during a Serie A match.
Earlier, two late goals from Federico Chiesa gave Fiorentina a 2-0 win at Torino.
(Reporting by Brian Homewood, editing by Ed Osmond)
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