MathDB

5

Part of 2021 JBMO TST - Turkey

Problems(1)

Reaching a perfect square with d(n) function

Source: 2021 Turkey JBMO TST 2021 P5

5/24/2021
d(n)d(n) shows the number of positive integer divisors of positive integer nn. For which positive integers nn one cannot find a positive integer kk such that d(…d(d⏟k times(n)… )\underbrace{d(\dots d(d}_{k\ \text{times}} (n) \dots ) is a perfect square.
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