Day 7: “Then God blessed the seventh day and made it holy, because on it he rested from all the work of creating that he had done.”
Look at the pattern you just rebuilt: Day 1 matches Day 4, Day 2 matches Day 5, and Day 3 matches Day 6.
Every “forming day” on the left has a “filling day” partner on the right.
But Day 7 stands alone with no matching pair.
The mathematical structure of the story itself is preaching a message:
the unmatched seventh day is the most important day in the whole week.
Everything else is arranged in pairs so that the Sabbath can stand out as the holy climax.