Recursive Formulas - Definition & Examples

A sequence is denoted by the following recursive formula: $$a_n = \left\{ \begin{array}{ll} 1 & \text{ if } n = 0 \\ 2 & \text{ if } n = 1 \\ 3a_{n-1} - 2a_{n-2} & \text{ if } n \geq 2 \end{array} \right.$$