3.
已知数列\(\{{{a}_{n}}\}\)各项均为正数,\({{S}_{n}}\)为其前\(n\)项和,满足\({{S}_{n}}={{(\dfrac{1+{{a}_{n}}}{2})}^{2}}\),
\((1)\)求\(\{{{a}_{n}}\}\)的通项公式;
\((2)\)令\({{b}_{n}}=a_{n}^{2},n\in {{N}^{*}}\),证明:\(\dfrac{1}{{{b}_{1}}}+\dfrac{1}{{{b}_{2}}}+\dfrac{1}{{{b}_{3}}}+\cdots +\dfrac{1}{{{b}_{n}}} < \dfrac{5}{4}\)