how to decode the sequence number

That's an 'arbitrary' number assigned to the vehicle while it is going through edit.

All orders are sent through edit before they are scheduled for the assembly line. Then wait in a pool until they are scheduled for production.

Contrary to popular belief, the sequence number is not the order that they come down the assembly line. Sometimes you can find some with sequential numbers on the line, but not often.

The car first goes through the body shop where the sheet metal is assembled/welded.

If any repairs are needed before paint, it goes to the repair area, when the "good" ones go right through to paint shop. - One area to get out of sequence.

Then there may be a paint repair if something happens in the paint shop. - another area to get out of sequence. Or if there is a two tone paint, they loop through twice where monotone paint goes through once. - more potential to get out of sequence before assembly.

Then it comes out of paint to the assembly line. If any repairs are needed/unfinished jobs at the end of the line, then it gets sent to another repair area while the good ones go to the "final line" and then to the " shipping line" where they are then driven out of the assembly plant and into the shipping lot at the factory. Once this happens, as far as the books are concerned they are now owned by the shipping company until they arrive to the dealer. To pull a vehicle back into the assembly plant after it has been driven out to the shipping lot requires a manager level approval.

There are many ways that the sequence numbers can get out of order when the vehicle is built. It does not indicate the order that they went down the assembly line.