MathNet 2026 — Part 09 Question 148

The Fibonacci sequence $F_{1}, F_{2}, F_{3}, \ldots$ is defined by $F_{1}=F_{2}=1$ and $F_{n+2}=F_{n+1}+F_{n}$. Find the least positive integer $t$ such that for all $n\gt 0$, $F_{n}=F_{n+t}$.