Suppose

Short Answer

Suppose $$\left\{ a _ { n } \right\} \text { is defined recursively by } a _ { n } = a _ { n - 1 } ^ { 2 } - 1 \text { and that } a _ { 0 } = 2 \text {. Find } a _ { 3 } \text { and } a _ { 4 } \text {. }$$