2017 IMO Problems/Problem 1

Revision as of 19:52, 22 November 2017 by Bobsonjoe (talk | contribs) (Created page with "For each integer <math>a_0 > 1</math>, define the sequence <math>a_0, a_1, a_2, \ldots</math> for <math>n \geq 0</math> as <cmath>a_{n+1} = \begin{cases} \sqrt{a_n} & \text{i...")
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

For each integer $a_0 > 1$, define the sequence $a_0, a_1, a_2, \ldots$ for $n \geq 0$ as \[a_{n+1} =  \begin{cases} \sqrt{a_n} & \text{if } \sqrt{a_n} \text{ is an integer,} \\ a_n + 3 & \text{otherwise.} \end{cases}\]Determine all values of $a_0$ such that there exists a number $A$ such that $a_n = A$ for infinitely many values of $n$.