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Cool-divisble numbers

Author: daniyar
Problem has been solved: 64 times

Русский язык | English Language



A number $ \overline {a_1a_2 ... a_k} $ is said to be cool-divisible if, for any $ n = 1,2, ..., k-1 $, the number $ \overline {a_na_ {n + 1}} $ is divisible by 17 or 23. Find the number of 2020-digit cool-divisible numbers.





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