בְּנֵ֥י גֵרְשׁ֛וֹן לִבְנִ֥י וְשִׁמְעִ֖י לְמִשְׁפְּחֹתָֽם׃
די זין פֿון גֵרשוֹנען: לִבני, און שִמעִי, לױט זײערע משפּחות.
Rabbeinu Bahya
ואלה פקודי הלוי למשפחותם לגרשון, “and these are the enrollments of the Levites according to their clans. Of Gershon, etc.” The Torah first mentions the oldest of Levi’s sons followed by Livni, Levis’s grandson but omitting Shimi (Exodus 6,17) as he had no sons, or they died during his life time leaving no male offspring (Ibn Ezra).