3.
设等差数列\(\{a_{n}\}\)的公差\(d > 0\),若\({{a}_{1}}+{{a}_{2}}+{{a}_{3}}=-9\),\({{a}_{1}}{{a}_{2}}{{a}_{3}}=-15\).
\((1)\)求数列\(\{a_{n}\}\)的通项公式;
\((2)\)求数列\(\{a_{n}\}\)的前\(n\)项和\({{s}_{n}};\)
\((3)\)试求所有的正整数\(m\),使得\(\dfrac{{{a}_{m}}{{a}_{m+1}}}{{{a}_{m+2}}}\)为数列\(\left\{ {{a}_{n}} \right\}\)中的项.