Q:

Can you fill in the gaps in this number sequence?

The number sequence is 
73, 70, 49, 52, 35, ?, ?, ?, ?, ?, 72,.....

Can you fill in the gaps and predict what happens after 72?
I have updated the hints below.
Hint 1

 What are the factors of each number? Calculate factors for each number!

Hint 2

 This is a mathematical problem, but does not require complicated maths

Hint 3

 If a sequence using exactly the same mathematical rules is started with a different number a different pattern develops.  For example; [ 1, 1, 1, 1, ........ ] and [ 48, 48, 48, 48, ........]

A:

The 5 missing values are:

 24, 12, 3, 9, 81

After 72:

 Each subsequent value will be 9 less until it gets to 9, then start over at 81, repeating forever.

The method:

 To calculate the next value, add the digits of the current value and multiply by the first digit of the current value.

