数列\(\left\{ {{a}_{n}} \right\}\)满足\({{a}_{1}}=4\)，\({{a}_{n}}=4-\dfrac{4}{{{a}_{n-1}}}\ \,(n\geqslant 2)\)，设\({{b}_{n}}{=}\dfrac{1}{{{a}_{n}}-2}\)．

\((1)\)判断数列\(\left\{ {{b}_{n}} \right\}\)是否为等差数列并试证明；

\((2)\)求数列\(\left\{ {{a}_{n}} \right\}\)的通项公式．