These were the descendants of Levi by their families—the heads of families, registered individually by name—those twenty years of age or older who worked in the service of the house of the LORD.
KJV
These [were] the sons of Levi after the house of their fathers; [even] the chief of the fathers, as they were counted by number of names by their polls, that did the work for the service of the house of the LORD, from the age of twenty years and upward.
ASV
These were the sons of Levi after their fathers’ houses, even the heads of the fathers’ houses of those of them that were counted, in the number of names by their polls, who did the work for the service of the house of Jehovah, from twenty years old and upward.