8.
已知\(\{a_{n}\}\)是等差数列,\(\{b_{n}\}\)是等比数列,其中\(a_{1}=b_{1}=1\),\(a_{2}+b_{3}=a_{4}\),\(a_{3}+b_{4}=a_{7}\).
\((\)Ⅰ\()\)求数列\(\{a_{n}\}\)与\(\{b_{n}\}\)的通项公式;
\((\)Ⅱ\()\)记\(c_{n}= \dfrac {1}{n}(a_{1}+a_{2}+…+a_{n})(b_{1}+b_{2}+…+b_{n})\),求数列\(\{c_{n}\}\)的前\(n\)项和\(S_{n}\).