Usage: 2 forms in 2 verses
Form Translated As     In Verse(s)
περιεκάθητο were besieging LXX.1Kgs.15.27
περιεκάθηντο they laid siege LXX.2Kgs.6.25

Liddell-Scott-Jones

περικάθημαι (perikathēmai) to besiege G:V

περικάθημαι-ημαι,

Ionic dialect περι-κάτημαι, Ionic dialect 3rd.pers. plural imperfect περιεκατέατο or περικατέατο [Refs 5th c.BC+]:—to be seated all round, τραπέζῃ at table, [Refs] codices: mostly c.accusative, invest, besiege a town, τὴν Νίνον [LXX]; also περιεκάθητο ἐπὶ Ταβαθών[LXX]; of ships, blockade, [Refs 5th c.BC+]: c.accusative person, sit down by one as a companion, [Refs]

LSJ Scripture Refs: LXX.Judg.9.31LXX.1Kgs.15.27