Skip to content / Đến nội dung
ThichHocToan.com

MathNet 2025-part-01 — 187 problems (EN–VI) Question 122

Math Olympiad Vault · MathNet 2025-part-01 — 187 problems (EN–VI)

Question 122

For the real number sequence $\{a_n\}_{n=1}^{\infty}$, we are given that $a_1 = 1$, $a_2 = 3$, and for $n \ge 1$,
$$
a_{n+2} = a_{n+1} + \frac{3a_{n+1} - 1}{a_{n+1} - a_n}
$$
Prove that the terms of the sequence $\{a_n\}$ are natural numbers and find the term $a_{61}$.
(Otgonbayar Uuye)