——More and more students wear glasses in our school these days.——I agree with you. Students ___ keep on doing eye exercises to protect their eyes.
已知数列{an}是公差不为零的等差数列，a1=1且a1，a3，a9成等比数列．
（Ⅰ）求数列{an}的通项公式；
（Ⅱ）若bn=4an+2an求数列{bn}的前n项和Sn．
