'Seventeen' signifies both the beginning and the end of temptation, because it is made up of the numbers seven and ten. This number, when it means the beginning of temptation, implies a state 'for seven days,' or 'the seventh of seven days,' which means the beginning of temptation. When it means the end of temptation, then seven is a holy number to which ten is added, which means remains of good and truth. Without these remains, a person cannot be regenerated.

'The seventeenth day,' as in Genesis 8:4, means something is new.

(Reference: Arcana Coelestia 755)