Kabbalah do Liczb 3:2

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.