MathDB

5

Part of 2009 Cuba MO

Problems(1)

(5^n-1)/(n+2) is integer

Source: 2009 Cuba 2.5

8/27/2024
Prove that there are infinitely many positive integers nn such that 5n−1n+2\frac{5^n-1}{n+2} is an integer.
number theoryInteger