According to the book of Jude, Enoch is identified as being the seventh from Adam:
And Enoch also, the seventh from Adam, prophesied of these, saying,
Behold, the Lord cometh with ten thousands of his saints, To execute
judgment upon all, and to convince all that are ungodly among them of
all their ungodly deeds which they have ungodly committed, and of all
their hard speeches which ungodly sinners have spoken against him.
(Jude 1:14-15 KJV)
And it appears that he is referring to the seventh generation from Adam. This same terminology is used in the Book of Enoch, chapter 43, verse 3 in the Prophecy of Weeks, saying he was born seventh in the first week (or the first seven):
- And Enoch began to recount from the books and said: 'I was born the seventh in the first week, While judgement and righteousness still
Then, he proceeds to lay out a series of "weeks" with identifiable figures and/or events in each week. Based on the generations given in the Bible from Adam all the way to King David, it appears that there are no gaps in the generations when lining up the notable figures in this prophecy with those generations.
For example, Enoch is identified as being born the 7th from Adam, and that would be the first "week". The prophecy continues:
- And after me there shall arise in the second week great wickedness, And deceit shall have sprung up; And in it there shall be the first
And in it a man shall be saved; And after it is ended unrighteousness
shall grow up, And a law shall be made for the sinners.
- And after that in the third week at its close A man shall be elected as the plant of righteous judgement, And his posterity shall
become the plant of righteousness for evermore.
The close of the third week would be 21 generations (7 x 3). The 21st generation from Adam is Abraham.
Genesis 5 lays out the generations from Adam to Noah's sons and then Genesis 11:10-26 lays out the generations from Noah's son, Shem, to Abram, which adds up to a total of 21 generations.
The prophecy in Enoch continues:
And after that in the fourth week, at its close, Visions of the holy and righteous shall be seen, And a law for all generations and an
enclosure shall be made for them.
And after that in the fifth week, at its close, The house of glory and dominion shall be built for ever.
Both Matthew 1 and Luke 3 provide the generations from Abraham to David, which can be verified in various accounts in the Old Testament.
The close of the fifth week would be 35 generations (7 x 5). The 35th generation from Adam is Solomon.
[I quoted from the RH Charles' translation of the Book of Enoch: http://www.sacred-texts.com/bib/boe/boe096.htm ]