matthew 1:17 So all the generations from Abraham to David are fourteen generations; and from David until the carrying away into Babylon are fourteen generations; and from the carrying away into Babylon unto Christ are fourteen generations. - Free Bible Online

      17. So all the generations from Abraham to David are fourteen generations; and from David until the carrying away--or migration.
      into Babylon are fourteen generations; and from the carrying away into Babylon--the migration of Babylon.
      unto Christ are fourteen generations--that is, the whole may be conveniently divided into three fourteens, each embracing one marked era, and each ending with a notable event, in the Israelitish annals. Such artificial aids to memory were familiar to the Jews, and much larger gaps than those here are found in some of the Old Testament genealogies. In Ezr 7:1-5 no fewer than six generations of the priesthood are omitted, as will appear by comparing it with 1Ch 6:3-15. It will be observed that the last of the three divisions of fourteen appears to contain only thirteen distinct names, including Jesus as the last. LANGE thinks that this was meant as a tacit hint that Mary was to be supplied, as the thirteenth link of the last chain, as it is impossible to conceive that the Evangelist could have made any mistake in the matter. But there is a simpler way of accounting for it. As the Evangelist himself (Mt 1:17) reckons David twice--as the last of the first fourteen and the first of the second--so, if we reckon the second fourteen to end with Josiah, who was coeval with the "carrying away into captivity" (Mt 1:11), and third to begin with Jeconiah, it will be found that the last division, as well as the other two, embraces fourteen names, including that of our Lord.

JFB.