MathDB
2020 PUMaC Team 6

Source:

January 1, 2022
number theory

Problem Statement

We say that a string of digits from 00 to 99 is valid if the following conditions hold: First, for 2≤k≤42 \le k \le 4, no consecutive run of kk digits sums to a multiple of 1010. Second, between any two 00s, there are at least 33 other digits. Find the last four digits of the number of valid strings of length 20202020.
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