1. The problem is to understand and analyze the concept of a sequence (suite in French). 2. A sequence is an ordered list of numbers defined by a specific rule or formula. 3. The general term of a sequence is often denoted as $u_n$, where $n$ is the position in the sequence. 4. For example, if the sequence is defined by $u_n = 2n + 1$, then the first term $u_1 = 2 \times 1 + 1 = 3$, the second term $u_2 = 2 \times 2 + 1 = 5$, and so on. 5. Important rules include: - The index $n$ usually starts at 1 or 0. - Each term depends on $n$ or previous terms. 6. To find any term, substitute the value of $n$ into the formula. 7. If the sequence is recursive, each term depends on previous terms, e.g., $u_{n+1} = u_n + 3$ with $u_1 = 2$. 8. Understanding sequences helps in many areas of mathematics and science.