## 1.1 Recurrence Relations and Sequences

### Sequence

A list of numbers written down in succession.

**Terms of a Sequence**

The terms of a sequence can be identified by their term numbers.

The initial term or 0th term is A_{0}; The first term is A_{1};The second term is A_{2}.

A_{0}, A_{1}, A_{2}

The 𝑛th term is 𝑢; The term before the 𝑛th term is 𝑢; The term after the 𝑛th term is 𝑢.

A_{n-1}, A_{n}, A_{n+1}

Any letter, not just A, can represent the terms of a sequence.