Career
Hartmann composed melodies to a number of songs, including Prøysen"s "Musevisa", "Romjulsdrøm" and "Æille har et syskjenbån på Gjøvik", and Skjæraasen"s "Høstvise" and "Åtte øyne i hverandre". His cooperation with Thorbjørn Egner resulted in music to songs from Karius and Bactus, Doktor Dyregod and Dyrene i Hakkebakkeskogen. Film music includes compositions for Finn Bø and Titus Vibe-Müller"s 1946 film To liv and Per Høst"s 1957 film Same-Jakki.