4.
已知数列\(\left\{{a}_{n}\right\} \),\(\left\{{b}_{n}\right\} \)都是单调递增数列,若将这两个数列的项按由小到大的顺序排成一列\((\)相同的项视为一项\()\),则得到一个新数列\(\left\{{c}_{n}\right\} \)
\((1)\)设数列\(\left\{{a}_{n}\right\} \),\(\left\{{b}_{n}\right\} \)分别为等差、等比数列,若\({a}_{1}={b}_{1}=1,{a}_{2}={b}_{3},{a}_{6}={b}_{5} \),求\(c_{20}\);
\((2)\)设\(\left\{{a}_{n}\right\} \)的首项为\(1\),各项为正整数,\({b}_{n}={3}^{n} \),若新数列\(\left\{{c}_{n}\right\} \)是等差数列,求数列\(\left\{{c}_{n}\right\} \) 的前\(n\)项和\(S_{n}\);
\((3)\)设\({b}_{n}={q}^{n-1} (q\)是不小于\(2\)的正整数\()c_{1}=b_{1}\),是否存在等差数列\(\left\{{a}_{n}\right\} \),使得对任意的\(n∈{N}^{*} \),在\(b\)\(n\)与\(b\)\(n+1\)之间数列\(\left\{{a}_{n}\right\} \)的项数总是\(b_{n}\)?若存在,请给出一个满足题意的等差数列\(\left\{{a}_{n}\right\} \);若不存在,请说明理由.