The song is "Hum bhole the hum bhale hain.".
"This is Susmit's last song with the band," said a source close to the band.
Sen has virtually invented a new style of playing the guitar and this formed the basis of creating Indian Ocean in 1990.
The band has delivered many hits like "Bandeh", "Kandisa" and "Out of the blues". Sen and singer Rahul Ram were the oldest in the current group.