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Problem 520 Published on Saturday, 13th June 2015, 10:00 pm; Solved by 297;
Difficulty rating: 45%

We define a simber to be a positive integer in which any odd digit, if present, occurs an odd number of times, and any even digit, if present, occurs an even number of times.

For example, 141221242 is a 9-digit simber because it has three 1's, four 2's and two 4's.

Let Q(n) be the count of all simbers with at most n digits.

You are given Q(7) = 287975 and Q(100) mod 1 000 000 123 = 123864868.

Find (∑1≤u≤39 Q(2u)) mod 1 000 000 123.