or -factorial is the product of all integers from up to . Let's denote be the product of all factorials from up to . Find the maximum integral value of such that divides
You may also try these problem:
Divisible by this year??? (Part 2: Factorials)
This problem is part of the set " Symphony "
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In this question, we only need to consider the prime factors of 2014: 2, 19, and 53.
Since 2, 19, and 53 are pairwise coprime , we will not overcount and thus we can further simplify the question by looking at the maximal k for which 5 3 k ∣ 2 0 1 4 ! ! .
Notice that 2 0 1 4 ! ! = 1 2 0 1 4 × 2 2 0 1 3 × … × 2 0 1 4 .
We begin by checking all factors of 2 0 1 4 ! ! of the form ( 5 3 n ) 2 0 1 5 − 5 3 n ; they have 5 3 2 0 1 5 − 5 3 n as a factor, and there are 38 such integers; hence, a lower bound for k = n = 1 ∑ 3 8 2 0 1 5 − 5 3 n = 3 7 2 9 7 .
Then, we check all factors of the form ( 5 3 2 n ) 2 0 1 5 − 5 3 2 n ; however, because 5 3 2 > 2 0 1 4 ! , there are no more factors to check and hence our answer is k = 3 7 2 9 7 .