וְאֵ֛לֶּה שְׁמ֥וֹת בְּֽנֵי־אַהֲרֹ֖ן הַבְּכ֣וֹר ׀ נָדָ֑ב וַאֲבִיה֕וּא אֶלְעָזָ֖ר וְאִיתָמָֽר׃
И вот имена сынов Аарона: Надав, первенец, и Авиух, Елеазар и Итамар.
Zohar
We have learned that it is written, "These are the names of the sons of Aaron, the priests" (Bemidbar 3:3) and also, "Nadab the firstborn, and Abihu, Elazar and Itamar" (Ibid. 2). It should read: 'And Elazar and Itamar" so why write "Elazar and Itamar?" (i.e. why delete the Vav). Abihu was equal to his two brothers and Nadab is equal to all the others.