123 Numbers (noch nicht übersetzt)

Problem 698

We define 123-numbers as follows:

  • 1 is the smallest 123-number.
  • When written in base 10 the only digits that can be present are "1", "2" and "3" and if present the number of times they each occur is also a 123-number.

So 2 is a 123-number, since it consists of one digit "2" and 1 is a 123-number. Therefore, 33 is a 123-number as well since it consists of two digits "3" and 2 is a 123-number.
On the other hand, 1111 is not a 123-number, since it contains 4 digits "1" and 4 is not a 123-number.

In ascending order, the first 123-numbers are:
1,2,3,11,12,13,21,22,23,31,32,33,111,112,113,121,122,123,131,

Let F(n) be the n-th 123-number. For example F(4)=11, F(10)=31, F(40)=1112, F(1000)=1223321 and F(6000)=2333333333323.

Find F(111111111111222333). Give your answer modulo 123123123.